diff --git a/README.md b/README.md
index 4b93c2f..f43b091 100644
--- a/README.md
+++ b/README.md
@@ -599,11 +599,12 @@ Ogooreck provides a set of helpers to construct the request (e.g. `URI`, `BODY`)
 
 ```csharp
 public Task POST_CreatesNewMeeting() =>
-    API.Given(
+    API.Given()
+        .When(
+            POST
             URI("/api/meetings/),
             BODY(new CreateMeeting(Guid.NewGuid(), "Event Sourcing Workshop"))
         )
-        .When(POST)
         .Then(CREATED);
 ```
 
@@ -613,11 +614,12 @@ You can also specify headers, e.g. `IF_MATCH` to perform an optimistic concurren
 
 ```csharp
 public Task PUT_ConfirmsShoppingCart() =>
-    API.Given(
+    API.Given()
+        .When(
+            PUT,
             URI($"/api/ShoppingCarts/{API.ShoppingCartId}/confirmation"),
             HEADERS(IF_MATCH(1))
         )
-        .When(PUT)
         .Then(OK);
 ```
 
@@ -627,10 +629,8 @@ You can also do response body assertions, to, e.g. out of the box check if the r
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
-            URI($"/api/ShoppingCarts/{API.ShoppingCartId}")
-        )
-        .When(GET)
+    API.Given()
+        .When(GET, URI($"/api/ShoppingCarts/{API.ShoppingCartId}"))
         .Then(
             OK,
             RESPONSE_BODY(new ShoppingCartDetails
@@ -649,10 +649,9 @@ You can use various conditions, e.g. `RESPONSE_SUCCEEDED` waits until a response
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
-            URI($"/api/ShoppingCarts/{API.ShoppingCartId}")
-        )
-        .When(GET_UNTIL(RESPONSE_SUCCEEDED))
+    API.Given()
+        .When(GET, URI($"/api/ShoppingCarts/{API.ShoppingCartId}"))
+        .Until(RESPONSE_SUCCEEDED)
         .Then(
             OK,
             RESPONSE_BODY(new ShoppingCartDetails
@@ -669,10 +668,9 @@ You can also use `RESPONSE_ETAG_IS` helper to check if ETag matches your expecte
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
-            URI($"/api/ShoppingCarts/{API.ShoppingCartId}")
-        )
-        .When(GET_UNTIL(RESPONSE_ETAG_IS(2)))
+    API.Given()
+        .When(GET, URI($"/api/ShoppingCarts/{API.ShoppingCartId}"))
+        .Until(RESPONSE_ETAG_IS(2))
         .Then(
             OK,
             RESPONSE_BODY(new ShoppingCartDetails
@@ -691,14 +689,15 @@ You can also do custom checks on the body, providing expression.
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
+    API.Given()
+        .When(
+            GET,
             URI($"{MeetingsSearchApi.MeetingsUrl}?filter={MeetingName}")
         )
-        .When(
-            GET_UNTIL(
-                RESPONSE_BODY_MATCHES<IReadOnlyCollection<Meeting>>(
-                    meetings => meetings.Any(m => m.Id == MeetingId))
-            ))
+        .UNTIL(
+            RESPONSE_BODY_MATCHES<IReadOnlyCollection<Meeting>>(
+                meetings => meetings.Any(m => m.Id == MeetingId))
+        )
         .Then(
             RESPONSE_BODY<IReadOnlyCollection<Meeting>>(meetings =>
                 meetings.Should().Contain(meeting =>
@@ -714,15 +713,47 @@ Of course, the delete keyword is also supported.
 
 ```csharp
 public Task DELETE_ShouldRemoveProductFromShoppingCart() =>
-    API.Given(
-            URI(
-                $"/api/ShoppingCarts/{API.ShoppingCartId}/products/{API.ProductItem.ProductId}?quantity={RemovedCount}&unitPrice={API.UnitPrice}"),
+    API.Given()
+        .When(
+            DELETE, 
+            URI($"/api/ShoppingCarts/{API.ShoppingCartId}/products/{API.ProductItem.ProductId}?quantity={RemovedCount}&unitPrice={API.UnitPrice}"),
             HEADERS(IF_MATCH(1))
         )
-        .When(DELETE)
         .Then(NO_CONTENT);
 ```
 
+### Using data from results of the previous tests
+
+For instance created id to shape proper URI.
+
+```csharp
+public class CancelShoppingCartTests: IClassFixture<ApiSpecification<Program>>
+{
+    private readonly ApiSpecification<Program> API;
+    public CancelShoppingCartTests(ApiSpecification<Program> api) => API = api;
+
+    public readonly Guid ClientId = Guid.NewGuid();
+
+    [Fact]
+    [Trait("Category", "Acceptance")]
+    public Task Delete_Should_Return_OK_And_Cancel_Shopping_Cart() =>
+        API
+            .Given(
+                "Opened ShoppingCart",
+                POST,
+                URI("/api/ShoppingCarts"),
+                BODY(new OpenShoppingCartRequest(clientId: Guid.NewGuid()))
+            )
+            .When(
+                "Cancel Shopping Cart",
+                DELETE,
+                URI(ctx => $"/api/ShoppingCarts/{ctx.GetCreatedId()}"),
+                HEADERS(IF_MATCH(0))
+            )
+            .Then(OK);
+}
+```
+
 ### Scenarios and advanced composition
 
 Ogooreck supports various ways of composing the API, e.g.
@@ -736,19 +767,21 @@ public async Task POST_WithExistingSKU_ReturnsConflictStatus() =>
     var request = new RegisterProductRequest("AA2039485", ValidName, ValidDescription);
 
     // first one should succeed
-    await API.Given(
+    await API.Given()
+        .When(
+            POST,
             URI("/api/products/"),
             BODY(request)
         )
-        .When(POST)
         .Then(CREATED);
 
     // second one will fail with conflict
-    await API.Given(
+    await API.Given()
+        .When(
+            POST,
             URI("/api/products/"),
             BODY(request)
         )
-        .When(POST)
         .Then(CONFLICT);
 }
 ```
@@ -756,23 +789,27 @@ public async Task POST_WithExistingSKU_ReturnsConflictStatus() =>
 **Joining with `And`**
 
 ```csharp
-public Task SendPackage_ShouldReturn_CreatedStatus_With_PackageId() =>
-        API.Given(
-                URI("/api/Shipments/"),
-                BODY(new SendPackage(OrderId, ProductItems))
-            )
-            .When(POST)
-            .Then(CREATED)
-            .And(response => fixture.ShouldPublishInternalEventOfType<PackageWasSent>(
-                @event =>
-                    @event.PackageId == response.GetCreatedId<Guid>()
-                    && @event.OrderId == OrderId
-                    && @event.SentAt > TimeBeforeSending
-                    && @event.ProductItems.Count == ProductItems.Count
-                    && @event.ProductItems.All(
-                        pi => ProductItems.Exists(
-                            expi => expi.ProductId == pi.ProductId && expi.Quantity == pi.Quantity))
-            ));
+public async Task POST_WithExistingSKU_ReturnsConflictStatus() =>
+{
+    // Given
+    var request = new RegisterProductRequest("AA2039485", ValidName, ValidDescription);
+
+    // first one should succeed
+    await API.Given()
+        .When(
+            POST,
+            URI("/api/products/"),
+            BODY(request)
+        )
+        .Then(CREATED)
+        .And()
+        .When(
+            POST,
+            URI("/api/products/"),
+            BODY(request)
+        )
+        .Then(CONFLICT);
+}
 ```
 
 **Chained Api Scenario**
@@ -784,11 +821,12 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
 
     await API.Scenario(
         // Create Reservations
-        API.Given(
+        API.Given()
+            .When(
+                POST,        
                 URI("/api/Reservations/"),
                 BODY(new CreateTentativeReservationRequest { SeatId = SeatId })
             )
-            .When(POST)
             .Then(CREATED,
                 response =>
                 {
@@ -797,10 +835,11 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
                 }),
 
         // Get reservation details
-        _ => API.Given(
+        _ => API.Given()
+            .When(
+                GET
                 URI($"/api/Reservations/{createdReservationId}")
             )
-            .When(GET)
             .Then(
                 OK,
                 RESPONSE_BODY<ReservationDetails>(reservation =>
@@ -813,10 +852,8 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
                 })),
 
         // Get reservations list
-        _ => API.Given(
-                URI("/api/Reservations/")
-            )
-            .When(GET)
+        _ => API.Given()
+            .When(GET, URI("/api/Reservations/"))
             .Then(
                 OK,
                 RESPONSE_BODY<PagedListResponse<ReservationShortInfo>>(reservations =>
@@ -836,10 +873,8 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
                 })),
 
         // Get reservation history
-        _ => API.Given(
-                URI($"/api/Reservations/{createdReservationId}/history")
-            )
-            .When(GET)
+        _ => API.Given()
+            .When(GET, URI($"/api/Reservations/{createdReservationId}/history"))
             .Then(
                 OK,
                 RESPONSE_BODY<PagedListResponse<ReservationHistory>>(reservations =>
@@ -875,11 +910,12 @@ public class CreateMeetingTests: IClassFixture<ApiSpecification<Program>>
 
     [Fact]
     public Task CreateCommand_ShouldPublish_MeetingCreateEvent() =>
-        API.Given(
+        API.Given()
+            .When(
+                POST, 
                 URI("/api/meetings/),
                 BODY(new CreateMeeting(Guid.NewGuid(), "Event Sourcing Workshop"))
             )
-            .When(POST)
             .Then(CREATED);
 }
 ```
@@ -890,42 +926,52 @@ public class CreateMeetingTests: IClassFixture<ApiSpecification<Program>>
 Sometimes you need to set up test data asynchronously (e.g. open a shopping cart before cancelling it). You might not want to pollute your tests code with test case setup or do more extended preparation. For that XUnit provides `IAsyncLifetime` interface. You can create a fixture derived from the `APISpecification` to benefit from built-in helpers and use it later in your tests.
 
 ```csharp
-public class CancelShoppingCartFixture: ApiSpecification<Program>, IAsyncLifetime
+public class GetProductDetailsFixture: ApiSpecification<Program>, IAsyncLifetime
 {
-    public Guid ShoppingCartId { get; private set; }
+    public ProductDetails ExistingProduct = default!;
+
+    public GetProductDetailsFixture(): base(new WarehouseTestWebApplicationFactory()) { }
 
     public async Task InitializeAsync()
     {
-        var openResponse = await Send(
-            new ApiRequest(POST, URI("/api/ShoppingCarts"), BODY(new OpenShoppingCartRequest(Guid.NewGuid())))
-        );
-
-        await CREATED(openResponse);
+        var registerProduct = new RegisterProductRequest("IN11111", "ValidName", "ValidDescription");
+        var productId = await Given()
+            .When(POST, URI("/api/products"), BODY(registerProduct))
+            .Then(CREATED)
+            .GetCreatedId<Guid>();
 
-        ShoppingCartId = openResponse.GetCreatedId<Guid>();
+        var (sku, name, description) = registerProduct;
+        ExistingProduct = new ProductDetails(productId, sku!, name!, description);
     }
 
-    public Task DisposeAsync()
-    {
-        Dispose();
-        return Task.CompletedTask;
-    }
+    public Task DisposeAsync() => Task.CompletedTask;
 }
 
-public class CancelShoppingCartTests: IClassFixture<CancelShoppingCartFixture>
+public class GetProductDetailsTests: IClassFixture<GetProductDetailsFixture>
 {
-    private readonly CancelShoppingCartFixture API;
+    private readonly GetProductDetailsFixture API;
 
-    public CancelShoppingCartTests(CancelShoppingCartFixture api) => API = api;
+    public GetProductDetailsTests(GetProductDetailsFixture api) => API = api;
 
     [Fact]
-    public async Task Delete_Should_Return_OK_And_Cancel_Shopping_Cart() => 
-        API.Given(
-                URI($"/api/ShoppingCarts/{API.ShoppingCartId}"),
-                HEADERS(IF_MATCH(1))
-            )
-            .When(DELETE)
-            .Then(OK);
+    public Task ValidRequest_With_NoParams_ShouldReturn_200() =>
+        API.Given()
+            .When(GET, URI($"/api/products/{API.ExistingProduct.Id}"))
+            .Then(OK, RESPONSE_BODY(API.ExistingProduct));
+
+    [Theory]
+    [InlineData(12)]
+    [InlineData("not-a-guid")]
+    public Task InvalidGuidId_ShouldReturn_404(object invalidId) =>
+        API.Given()
+            .When(GET, URI($"/api/products/{invalidId}"))
+            .Then(NOT_FOUND);
+
+    [Fact]
+    public Task NotExistingId_ShouldReturn_404() =>
+        API.Given()
+            .When(GET, URI($"/api/products/{Guid.NewGuid()}"))
+            .Then(NOT_FOUND);
 }
 ```
 
diff --git a/mdsource/README.source.md b/mdsource/README.source.md
index 4b93c2f..f43b091 100644
--- a/mdsource/README.source.md
+++ b/mdsource/README.source.md
@@ -599,11 +599,12 @@ Ogooreck provides a set of helpers to construct the request (e.g. `URI`, `BODY`)
 
 ```csharp
 public Task POST_CreatesNewMeeting() =>
-    API.Given(
+    API.Given()
+        .When(
+            POST
             URI("/api/meetings/),
             BODY(new CreateMeeting(Guid.NewGuid(), "Event Sourcing Workshop"))
         )
-        .When(POST)
         .Then(CREATED);
 ```
 
@@ -613,11 +614,12 @@ You can also specify headers, e.g. `IF_MATCH` to perform an optimistic concurren
 
 ```csharp
 public Task PUT_ConfirmsShoppingCart() =>
-    API.Given(
+    API.Given()
+        .When(
+            PUT,
             URI($"/api/ShoppingCarts/{API.ShoppingCartId}/confirmation"),
             HEADERS(IF_MATCH(1))
         )
-        .When(PUT)
         .Then(OK);
 ```
 
@@ -627,10 +629,8 @@ You can also do response body assertions, to, e.g. out of the box check if the r
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
-            URI($"/api/ShoppingCarts/{API.ShoppingCartId}")
-        )
-        .When(GET)
+    API.Given()
+        .When(GET, URI($"/api/ShoppingCarts/{API.ShoppingCartId}"))
         .Then(
             OK,
             RESPONSE_BODY(new ShoppingCartDetails
@@ -649,10 +649,9 @@ You can use various conditions, e.g. `RESPONSE_SUCCEEDED` waits until a response
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
-            URI($"/api/ShoppingCarts/{API.ShoppingCartId}")
-        )
-        .When(GET_UNTIL(RESPONSE_SUCCEEDED))
+    API.Given()
+        .When(GET, URI($"/api/ShoppingCarts/{API.ShoppingCartId}"))
+        .Until(RESPONSE_SUCCEEDED)
         .Then(
             OK,
             RESPONSE_BODY(new ShoppingCartDetails
@@ -669,10 +668,9 @@ You can also use `RESPONSE_ETAG_IS` helper to check if ETag matches your expecte
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
-            URI($"/api/ShoppingCarts/{API.ShoppingCartId}")
-        )
-        .When(GET_UNTIL(RESPONSE_ETAG_IS(2)))
+    API.Given()
+        .When(GET, URI($"/api/ShoppingCarts/{API.ShoppingCartId}"))
+        .Until(RESPONSE_ETAG_IS(2))
         .Then(
             OK,
             RESPONSE_BODY(new ShoppingCartDetails
@@ -691,14 +689,15 @@ You can also do custom checks on the body, providing expression.
 
 ```csharp
 public Task GET_ReturnsShoppingCartDetails() =>
-    API.Given(
+    API.Given()
+        .When(
+            GET,
             URI($"{MeetingsSearchApi.MeetingsUrl}?filter={MeetingName}")
         )
-        .When(
-            GET_UNTIL(
-                RESPONSE_BODY_MATCHES<IReadOnlyCollection<Meeting>>(
-                    meetings => meetings.Any(m => m.Id == MeetingId))
-            ))
+        .UNTIL(
+            RESPONSE_BODY_MATCHES<IReadOnlyCollection<Meeting>>(
+                meetings => meetings.Any(m => m.Id == MeetingId))
+        )
         .Then(
             RESPONSE_BODY<IReadOnlyCollection<Meeting>>(meetings =>
                 meetings.Should().Contain(meeting =>
@@ -714,15 +713,47 @@ Of course, the delete keyword is also supported.
 
 ```csharp
 public Task DELETE_ShouldRemoveProductFromShoppingCart() =>
-    API.Given(
-            URI(
-                $"/api/ShoppingCarts/{API.ShoppingCartId}/products/{API.ProductItem.ProductId}?quantity={RemovedCount}&unitPrice={API.UnitPrice}"),
+    API.Given()
+        .When(
+            DELETE, 
+            URI($"/api/ShoppingCarts/{API.ShoppingCartId}/products/{API.ProductItem.ProductId}?quantity={RemovedCount}&unitPrice={API.UnitPrice}"),
             HEADERS(IF_MATCH(1))
         )
-        .When(DELETE)
         .Then(NO_CONTENT);
 ```
 
+### Using data from results of the previous tests
+
+For instance created id to shape proper URI.
+
+```csharp
+public class CancelShoppingCartTests: IClassFixture<ApiSpecification<Program>>
+{
+    private readonly ApiSpecification<Program> API;
+    public CancelShoppingCartTests(ApiSpecification<Program> api) => API = api;
+
+    public readonly Guid ClientId = Guid.NewGuid();
+
+    [Fact]
+    [Trait("Category", "Acceptance")]
+    public Task Delete_Should_Return_OK_And_Cancel_Shopping_Cart() =>
+        API
+            .Given(
+                "Opened ShoppingCart",
+                POST,
+                URI("/api/ShoppingCarts"),
+                BODY(new OpenShoppingCartRequest(clientId: Guid.NewGuid()))
+            )
+            .When(
+                "Cancel Shopping Cart",
+                DELETE,
+                URI(ctx => $"/api/ShoppingCarts/{ctx.GetCreatedId()}"),
+                HEADERS(IF_MATCH(0))
+            )
+            .Then(OK);
+}
+```
+
 ### Scenarios and advanced composition
 
 Ogooreck supports various ways of composing the API, e.g.
@@ -736,19 +767,21 @@ public async Task POST_WithExistingSKU_ReturnsConflictStatus() =>
     var request = new RegisterProductRequest("AA2039485", ValidName, ValidDescription);
 
     // first one should succeed
-    await API.Given(
+    await API.Given()
+        .When(
+            POST,
             URI("/api/products/"),
             BODY(request)
         )
-        .When(POST)
         .Then(CREATED);
 
     // second one will fail with conflict
-    await API.Given(
+    await API.Given()
+        .When(
+            POST,
             URI("/api/products/"),
             BODY(request)
         )
-        .When(POST)
         .Then(CONFLICT);
 }
 ```
@@ -756,23 +789,27 @@ public async Task POST_WithExistingSKU_ReturnsConflictStatus() =>
 **Joining with `And`**
 
 ```csharp
-public Task SendPackage_ShouldReturn_CreatedStatus_With_PackageId() =>
-        API.Given(
-                URI("/api/Shipments/"),
-                BODY(new SendPackage(OrderId, ProductItems))
-            )
-            .When(POST)
-            .Then(CREATED)
-            .And(response => fixture.ShouldPublishInternalEventOfType<PackageWasSent>(
-                @event =>
-                    @event.PackageId == response.GetCreatedId<Guid>()
-                    && @event.OrderId == OrderId
-                    && @event.SentAt > TimeBeforeSending
-                    && @event.ProductItems.Count == ProductItems.Count
-                    && @event.ProductItems.All(
-                        pi => ProductItems.Exists(
-                            expi => expi.ProductId == pi.ProductId && expi.Quantity == pi.Quantity))
-            ));
+public async Task POST_WithExistingSKU_ReturnsConflictStatus() =>
+{
+    // Given
+    var request = new RegisterProductRequest("AA2039485", ValidName, ValidDescription);
+
+    // first one should succeed
+    await API.Given()
+        .When(
+            POST,
+            URI("/api/products/"),
+            BODY(request)
+        )
+        .Then(CREATED)
+        .And()
+        .When(
+            POST,
+            URI("/api/products/"),
+            BODY(request)
+        )
+        .Then(CONFLICT);
+}
 ```
 
 **Chained Api Scenario**
@@ -784,11 +821,12 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
 
     await API.Scenario(
         // Create Reservations
-        API.Given(
+        API.Given()
+            .When(
+                POST,        
                 URI("/api/Reservations/"),
                 BODY(new CreateTentativeReservationRequest { SeatId = SeatId })
             )
-            .When(POST)
             .Then(CREATED,
                 response =>
                 {
@@ -797,10 +835,11 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
                 }),
 
         // Get reservation details
-        _ => API.Given(
+        _ => API.Given()
+            .When(
+                GET
                 URI($"/api/Reservations/{createdReservationId}")
             )
-            .When(GET)
             .Then(
                 OK,
                 RESPONSE_BODY<ReservationDetails>(reservation =>
@@ -813,10 +852,8 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
                 })),
 
         // Get reservations list
-        _ => API.Given(
-                URI("/api/Reservations/")
-            )
-            .When(GET)
+        _ => API.Given()
+            .When(GET, URI("/api/Reservations/"))
             .Then(
                 OK,
                 RESPONSE_BODY<PagedListResponse<ReservationShortInfo>>(reservations =>
@@ -836,10 +873,8 @@ public async Task Post_ShouldReturn_CreatedStatus_With_CartId()
                 })),
 
         // Get reservation history
-        _ => API.Given(
-                URI($"/api/Reservations/{createdReservationId}/history")
-            )
-            .When(GET)
+        _ => API.Given()
+            .When(GET, URI($"/api/Reservations/{createdReservationId}/history"))
             .Then(
                 OK,
                 RESPONSE_BODY<PagedListResponse<ReservationHistory>>(reservations =>
@@ -875,11 +910,12 @@ public class CreateMeetingTests: IClassFixture<ApiSpecification<Program>>
 
     [Fact]
     public Task CreateCommand_ShouldPublish_MeetingCreateEvent() =>
-        API.Given(
+        API.Given()
+            .When(
+                POST, 
                 URI("/api/meetings/),
                 BODY(new CreateMeeting(Guid.NewGuid(), "Event Sourcing Workshop"))
             )
-            .When(POST)
             .Then(CREATED);
 }
 ```
@@ -890,42 +926,52 @@ public class CreateMeetingTests: IClassFixture<ApiSpecification<Program>>
 Sometimes you need to set up test data asynchronously (e.g. open a shopping cart before cancelling it). You might not want to pollute your tests code with test case setup or do more extended preparation. For that XUnit provides `IAsyncLifetime` interface. You can create a fixture derived from the `APISpecification` to benefit from built-in helpers and use it later in your tests.
 
 ```csharp
-public class CancelShoppingCartFixture: ApiSpecification<Program>, IAsyncLifetime
+public class GetProductDetailsFixture: ApiSpecification<Program>, IAsyncLifetime
 {
-    public Guid ShoppingCartId { get; private set; }
+    public ProductDetails ExistingProduct = default!;
+
+    public GetProductDetailsFixture(): base(new WarehouseTestWebApplicationFactory()) { }
 
     public async Task InitializeAsync()
     {
-        var openResponse = await Send(
-            new ApiRequest(POST, URI("/api/ShoppingCarts"), BODY(new OpenShoppingCartRequest(Guid.NewGuid())))
-        );
-
-        await CREATED(openResponse);
+        var registerProduct = new RegisterProductRequest("IN11111", "ValidName", "ValidDescription");
+        var productId = await Given()
+            .When(POST, URI("/api/products"), BODY(registerProduct))
+            .Then(CREATED)
+            .GetCreatedId<Guid>();
 
-        ShoppingCartId = openResponse.GetCreatedId<Guid>();
+        var (sku, name, description) = registerProduct;
+        ExistingProduct = new ProductDetails(productId, sku!, name!, description);
     }
 
-    public Task DisposeAsync()
-    {
-        Dispose();
-        return Task.CompletedTask;
-    }
+    public Task DisposeAsync() => Task.CompletedTask;
 }
 
-public class CancelShoppingCartTests: IClassFixture<CancelShoppingCartFixture>
+public class GetProductDetailsTests: IClassFixture<GetProductDetailsFixture>
 {
-    private readonly CancelShoppingCartFixture API;
+    private readonly GetProductDetailsFixture API;
 
-    public CancelShoppingCartTests(CancelShoppingCartFixture api) => API = api;
+    public GetProductDetailsTests(GetProductDetailsFixture api) => API = api;
 
     [Fact]
-    public async Task Delete_Should_Return_OK_And_Cancel_Shopping_Cart() => 
-        API.Given(
-                URI($"/api/ShoppingCarts/{API.ShoppingCartId}"),
-                HEADERS(IF_MATCH(1))
-            )
-            .When(DELETE)
-            .Then(OK);
+    public Task ValidRequest_With_NoParams_ShouldReturn_200() =>
+        API.Given()
+            .When(GET, URI($"/api/products/{API.ExistingProduct.Id}"))
+            .Then(OK, RESPONSE_BODY(API.ExistingProduct));
+
+    [Theory]
+    [InlineData(12)]
+    [InlineData("not-a-guid")]
+    public Task InvalidGuidId_ShouldReturn_404(object invalidId) =>
+        API.Given()
+            .When(GET, URI($"/api/products/{invalidId}"))
+            .Then(NOT_FOUND);
+
+    [Fact]
+    public Task NotExistingId_ShouldReturn_404() =>
+        API.Given()
+            .When(GET, URI($"/api/products/{Guid.NewGuid()}"))
+            .Then(NOT_FOUND);
 }
 ```
 
diff --git a/src/Ogooreck.Sample.Api.Tests/ApiTests.cs b/src/Ogooreck.Sample.Api.Tests/ApiTests.cs
index d7da25d..2362b27 100644
--- a/src/Ogooreck.Sample.Api.Tests/ApiTests.cs
+++ b/src/Ogooreck.Sample.Api.Tests/ApiTests.cs
@@ -13,8 +13,8 @@ public class Tests: IClassFixture<ApiSpecification<Program>>
 
     [Fact]
     public Task GetProducts() =>
-        API.Given(URI("/api/products"))
-            .When(GET)
+        API.Given()
+            .When(GET, URI("/api/products"))
             .Then(OK);
 
     #endregion ApiGetSample
@@ -24,11 +24,12 @@ public Task GetProducts() =>
 
     [Fact]
     public Task RegisterProduct() =>
-        API.Given(
+        API.Given()
+            .When(
+                POST,
                 URI("/api/products"),
                 BODY(new RegisterProductRequest("abc-123", "Ogooreck"))
             )
-            .When(POST)
             .Then(CREATED, RESPONSE_LOCATION_HEADER());
 
     #endregion ApiPostSample
diff --git a/src/Ogooreck/API/ApiSpecification.cs b/src/Ogooreck/API/ApiSpecification.cs
index 82054f8..f6439ac 100644
--- a/src/Ogooreck/API/ApiSpecification.cs
+++ b/src/Ogooreck/API/ApiSpecification.cs
@@ -1,236 +1,17 @@
-using System.ComponentModel;
-using System.Net;
-using System.Net.Http.Headers;
-using System.Net.Http.Json;
-using FluentAssertions;
-using Microsoft.AspNetCore.Mvc.Testing;
-using Newtonsoft.Json;
-using Ogooreck.Newtonsoft;
+using Microsoft.AspNetCore.Mvc.Testing;
 
 #pragma warning disable CS1591
 
 namespace Ogooreck.API;
 
-public static class ApiSpecification
-{
-    ///////////////////
-    ////   GIVEN   ////
-    ///////////////////
-    public static Func<HttpRequestMessage, HttpRequestMessage> URI(string uri) =>
-        URI(new Uri(uri, UriKind.RelativeOrAbsolute));
-
-    public static Func<HttpRequestMessage, HttpRequestMessage> URI(Uri uri) =>
-        request =>
-        {
-            request.RequestUri = uri;
-            return request;
-        };
-
-    public static Func<HttpRequestMessage, HttpRequestMessage> BODY<T>(T body) =>
-        request =>
-        {
-            request.Content = JsonContent.Create(body);
-
-            return request;
-        };
-
-    public static Func<HttpRequestMessage, HttpRequestMessage> HEADERS(params Action<HttpRequestHeaders>[] headers) =>
-        request =>
-        {
-            foreach (var header in headers)
-            {
-                header(request.Headers);
-            }
-
-            return request;
-        };
-
-    public static Action<HttpRequestHeaders> IF_MATCH(string ifMatch, bool isWeak = true) =>
-        headers => headers.IfMatch.Add(new EntityTagHeaderValue($"\"{ifMatch}\"", isWeak));
-
-    public static Action<HttpRequestHeaders> IF_MATCH(object ifMatch, bool isWeak = true) =>
-        IF_MATCH(ifMatch.ToString()!, isWeak);
-
-    public static Task<HttpResponseMessage> And(this Task<HttpResponseMessage> response,
-        Func<HttpResponseMessage, HttpResponseMessage> and) =>
-        response.ContinueWith(t => and(t.Result));
-
-    public static Task And(this Task<HttpResponseMessage> response, Func<HttpResponseMessage, Task> and) =>
-        response.ContinueWith(t => and(t.Result));
-
-    public static Task And<TResult>(this Task<HttpResponseMessage> response, Func<HttpResponseMessage, Task<TResult>> and) =>
-        response.ContinueWith(t => and(t.Result));
-
-    public static Task And(this Task<HttpResponseMessage> response, Func<Task> and) =>
-        response.ContinueWith(_ => and());
-
-    public static Task And(this Task<HttpResponseMessage> response, Task and) =>
-        response.ContinueWith(_ => and);
-
-    ///////////////////
-    ////   WHEN    ////
-    ///////////////////
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> GET = SEND(HttpMethod.Get);
-
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> GET_UNTIL(
-        Func<HttpResponseMessage, ValueTask<bool>> check) =>
-        SEND_UNTIL(HttpMethod.Get, check);
+public delegate HttpRequestMessage RequestTransform(HttpRequestMessage request, TestContext context);
 
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> POST = SEND(HttpMethod.Post);
-
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> PUT = SEND(HttpMethod.Put);
-
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> DELETE = SEND(HttpMethod.Delete);
-
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> SEND(HttpMethod httpMethod) =>
-        (api, buildRequest) =>
-        {
-            var request = buildRequest();
-            request.Method = httpMethod;
-            return api.SendAsync(request);
-        };
-
-    public static Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> SEND_UNTIL(HttpMethod httpMethod,
-        Func<HttpResponseMessage, ValueTask<bool>> check, int maxNumberOfRetries = 5, int retryIntervalInMs = 1000) =>
-        async (api, buildRequest) =>
-        {
-            var retryCount = maxNumberOfRetries;
-            var finished = false;
-
-            HttpResponseMessage? response = null;
-            do
-            {
-                try
-                {
-                    var request = buildRequest();
-                    request.Method = httpMethod;
-
-                    response = await api.SendAsync(request);
-
-                    finished = await check(response);
-                }
-                catch
-                {
-                    if (retryCount == 0)
-                        throw;
-                }
-
-                await Task.Delay(retryIntervalInMs);
-                retryCount--;
-            } while (!finished);
-
-            response.Should().NotBeNull();
-
-            return response!;
-        };
-
-    ///////////////////
-    ////   THEN    ////
-    ///////////////////
-    public static Func<HttpResponseMessage, ValueTask> OK = HTTP_STATUS(HttpStatusCode.OK);
-    public static Func<HttpResponseMessage, ValueTask> CREATED = HTTP_STATUS(HttpStatusCode.Created);
-    public static Func<HttpResponseMessage, ValueTask> NO_CONTENT = HTTP_STATUS(HttpStatusCode.NoContent);
-    public static Func<HttpResponseMessage, ValueTask> BAD_REQUEST = HTTP_STATUS(HttpStatusCode.BadRequest);
-    public static Func<HttpResponseMessage, ValueTask> NOT_FOUND = HTTP_STATUS(HttpStatusCode.NotFound);
-    public static Func<HttpResponseMessage, ValueTask> CONFLICT = HTTP_STATUS(HttpStatusCode.Conflict);
-    public static Func<HttpResponseMessage, ValueTask> PRECONDITION_FAILED =
-        HTTP_STATUS(HttpStatusCode.PreconditionFailed);
-    public static Func<HttpResponseMessage, ValueTask> METHOD_NOT_ALLOWED =
-        HTTP_STATUS(HttpStatusCode.MethodNotAllowed);
-
-    public static Func<HttpResponseMessage, ValueTask> HTTP_STATUS(HttpStatusCode status) =>
-        response =>
-        {
-            response.StatusCode.Should().Be(status);
-            return ValueTask.CompletedTask;
-        };
-
-
-    public static Func<HttpResponseMessage, ValueTask> CREATED_WITH_DEFAULT_HEADERS(
-        string? locationHeaderPrefix = null, object? eTag = null, bool isETagWeak = true) =>
-        async response =>
-        {
-            await CREATED(response);
-            await RESPONSE_LOCATION_HEADER(locationHeaderPrefix)(response);
-            if(eTag != null)
-                await RESPONSE_ETAG_HEADER(eTag, isETagWeak)(response);
-        };
-
-    public static Func<HttpResponseMessage, ValueTask> RESPONSE_BODY<T>(T body) =>
-        RESPONSE_BODY<T>(result => result.Should().BeEquivalentTo(body));
-
-    public static Func<HttpResponseMessage, ValueTask> RESPONSE_BODY<T>(Action<T> assert) =>
-        async response =>
-        {
-            var result = await response.GetResultFromJson<T>();
-            assert(result);
-
-            result.Should().BeEquivalentTo(result);
-        };
-
-    public static Func<HttpResponseMessage, ValueTask<bool>> RESPONSE_ETAG_IS(object eTag, bool isWeak = true) =>
-        async response =>
-        {
-            await RESPONSE_ETAG_HEADER(eTag, isWeak)(response);
-            return true;
-        };
-
-    public static Func<HttpResponseMessage, ValueTask> RESPONSE_ETAG_HEADER(object eTag, bool isWeak = true) =>
-        RESPONSE_HEADERS(headers =>
-        {
-            headers.ETag.Should().NotBeNull("ETag response header should be defined").And.NotBe("", "ETag response header should not be empty");
-            headers.ETag!.Tag.Should().NotBeEmpty("ETag response header should not be empty");
-
-            headers.ETag.IsWeak.Should().Be(isWeak, "Etag response header should be {0}", isWeak? "Weak": "Strong");
-            headers.ETag.Tag.Should().Be($"\"{eTag}\"");
-        });
-
-    public static Func<HttpResponseMessage, ValueTask> RESPONSE_LOCATION_HEADER(string? locationHeaderPrefix = null) =>
-        async response =>
-        {
-            await HTTP_STATUS(HttpStatusCode.Created)(response);
-
-            var locationHeader = response.Headers.Location;
-
-            locationHeader.Should().NotBeNull();
-
-            var location = locationHeader!.ToString();
-
-            location.Should().StartWith(locationHeaderPrefix ?? response.RequestMessage!.RequestUri!.AbsolutePath);
-        };
-    public static Func<HttpResponseMessage, ValueTask> RESPONSE_HEADERS(params Action<HttpResponseHeaders>[] headers) =>
-        response =>
-        {
-            foreach (var header in headers)
-            {
-                header(response.Headers);
-            }
-            return ValueTask.CompletedTask;
-        };
-
-    public static Func<HttpResponseMessage, ValueTask<bool>> RESPONSE_SUCCEEDED() =>
-        response =>
-        {
-            response.EnsureSuccessStatusCode();
-            return new ValueTask<bool>(true);
-        };
-
-    public static Func<HttpResponseMessage, ValueTask<bool>> RESPONSE_BODY_MATCHES<TBody>(Func<TBody, bool> assert) =>
-        async response =>
-        {
-            response.EnsureSuccessStatusCode();
-
-            var result = await response.GetResultFromJson<TBody>();
-            result.Should().NotBeNull();
-
-            return assert(result);
-        };
-}
+public delegate ValueTask ResponseAssert(HttpResponseMessage response, TestContext context);
 
 public class ApiSpecification<TProgram>: IDisposable where TProgram : class
 {
     private readonly WebApplicationFactory<TProgram> applicationFactory;
-    private readonly HttpClient client;
+    private readonly Func<HttpClient> createClient;
 
     public ApiSpecification(): this(new WebApplicationFactory<TProgram>())
     {
@@ -239,43 +20,40 @@ public ApiSpecification(): this(new WebApplicationFactory<TProgram>())
     protected ApiSpecification(WebApplicationFactory<TProgram> applicationFactory)
     {
         this.applicationFactory = applicationFactory;
-        client = applicationFactory.CreateClient();
+        createClient = applicationFactory.CreateClient;
     }
 
     public static ApiSpecification<TProgram> Setup(WebApplicationFactory<TProgram> applicationFactory) =>
         new(applicationFactory);
 
-    public async Task<HttpResponseMessage> Send(ApiRequest apiRequest) =>
-        (await Send(new[] { apiRequest })).Single();
-
-    public async Task<HttpResponseMessage[]> Send(params ApiRequest[] apiRequests)
-    {
-        var responses = new List<HttpResponseMessage>();
+    public GivenApiSpecificationBuilder Given(
+        params RequestDefinition[] builders
+    ) =>
+        Given(builders.Select(b => new ApiTestStep(TestPhase.Given, b)).ToArray());
 
-        foreach (var request in apiRequests)
-        {
-            responses.Add(await client.Send(request));
-        }
 
-        return responses.ToArray();
-    }
+    public GivenApiSpecificationBuilder Given(
+        string description,
+        params RequestDefinition[] builders
+    ) =>
+        Given(builders.Select(b => new ApiTestStep(TestPhase.Given, b, description)).ToArray());
 
     public GivenApiSpecificationBuilder Given(
-        params Func<HttpRequestMessage, HttpRequestMessage>[] builders) =>
-        new(client, builders);
+        ApiTestStep[] builders) =>
+        new(new TestContext(), createClient, builders);
 
-    public async Task<HttpResponseMessage> Scenario(
-        Task<HttpResponseMessage> first,
-        params Func<HttpResponseMessage, Task<HttpResponseMessage>>[] following)
+    public async Task<ApiSpecification.Result> Scenario(
+        Task<ApiSpecification.Result> first,
+        params Func<HttpResponseMessage, Task<ApiSpecification.Result>>[] following)
     {
-        var response = await first;
+        var result = await first;
 
         foreach (var next in following)
         {
-            response = await next(response);
+            result = await next(result.Response);
         }
 
-        return response;
+        return result;
     }
 
     public async Task<HttpResponseMessage> Scenario(
@@ -292,183 +70,35 @@ public async Task<HttpResponseMessage> Scenario(
         return response;
     }
 
-    /////////////////////
-    ////   BUILDER   ////
-    /////////////////////
-
-    public class GivenApiSpecificationBuilder
-    {
-        private readonly Func<HttpRequestMessage, HttpRequestMessage>[] given;
-        private readonly HttpClient client;
-
-        internal GivenApiSpecificationBuilder(HttpClient client, Func<HttpRequestMessage, HttpRequestMessage>[] given)
-        {
-            this.client = client;
-            this.given = given;
-        }
-
-        public WhenApiSpecificationBuilder When(Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> when) =>
-            new(client, given, when);
-    }
-
-    public class WhenApiSpecificationBuilder
-    {
-        private readonly Func<HttpRequestMessage, HttpRequestMessage>[] given;
-        private readonly Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> when;
-        private readonly HttpClient client;
-
-        internal WhenApiSpecificationBuilder(
-            HttpClient client,
-            Func<HttpRequestMessage, HttpRequestMessage>[] given,
-            Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> when
-        )
-        {
-            this.client = client;
-            this.given = given;
-            this.when = when;
-        }
-
-        public Task<HttpResponseMessage> Then(Func<HttpResponseMessage, ValueTask> then) =>
-            Then(new[] { then });
-
-        public async Task<HttpResponseMessage> Then(params Func<HttpResponseMessage, ValueTask>[] thens)
-        {
-            var request = new ApiRequest(when, given);
-
-            var response = await client.Send(request);
-
-            foreach (var then in thens)
-            {
-                await then(response);
-            }
-
-            return response;
-        }
-    }
-
-    public void Dispose()
-    {
-        client.Dispose();
+    public void Dispose() =>
         applicationFactory.Dispose();
-    }
 }
 
-public class AndSpecificationBuilder
+public class TestApiRequest
 {
-    private readonly Lazy<Task<HttpResponseMessage>> then;
+    private readonly RequestTransform[] builders;
+    private readonly TestContext testContext;
 
-    public AndSpecificationBuilder(Lazy<Task<HttpResponseMessage>> then)
+    public TestApiRequest(TestContext testContext, params RequestTransform[] builders)
     {
-        this.then = then;
-    }
-
-    public Task<HttpResponseMessage> Response => then.Value;
-}
-
-public class ApiRequest
-{
-    private readonly Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> send;
-    private readonly Func<HttpRequestMessage, HttpRequestMessage>[] builders;
-
-    public ApiRequest(
-        Func<HttpClient, Func<HttpRequestMessage>, Task<HttpResponseMessage>> send,
-        params Func<HttpRequestMessage, HttpRequestMessage>[] builders
-    )
-    {
-        this.send = send;
+        this.testContext = testContext;
         this.builders = builders;
     }
 
-    public Task<HttpResponseMessage> Send(HttpClient httpClient)
-    {
-        HttpRequestMessage BuildRequest() =>
-            builders.Aggregate(new HttpRequestMessage(), (request, build) => build(request));
+    public HttpRequestMessage Build() =>
+        builders.Aggregate(new HttpRequestMessage(), (request, build) => build(request, testContext));
 
-        return send(httpClient, BuildRequest);
-    }
+    public static HttpRequestMessage For(TestContext testContext, RequestDefinition requestDefinition) =>
+        requestDefinition.Transformations
+            .Aggregate(new HttpRequestMessage(), (request, build) => build(request, testContext));
 }
 
 public static class ApiRequestExtensions
 {
-    public static Task<HttpResponseMessage> Send(this HttpClient httpClient, ApiRequest apiRequest) =>
-        apiRequest.Send(httpClient);
-}
-
-public static class HttpResponseMessageExtensions
-{
-    public static bool TryGetCreatedId<T>(this HttpResponseMessage response, out T? value)
-    {
-        value = default;
-
-        var locationHeader = response.Headers.Location?.OriginalString.TrimEnd('/');
-
-        if (string.IsNullOrEmpty(locationHeader))
-            return false;
-
-        locationHeader = locationHeader.StartsWith("/") ? locationHeader: $"/{locationHeader}";
-
-        var start = locationHeader.LastIndexOf("/", locationHeader.Length - 1);
-
-        var createdId = locationHeader.Substring(start + 1, locationHeader.Length - 1 - start);
-
-        var result = TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(createdId);
-
-        if (result == null)
-            return false;
-
-        value = (T?)result;
-
-        return true;
-    }
-
-    public static T GetCreatedId<T>(this HttpResponseMessage response) =>
-        response.TryGetCreatedId<T>(out var createdId)
-            ? createdId!
-            : throw new ArgumentOutOfRangeException(nameof(response.Headers.Location));
-
-    public static string GetCreatedId(this HttpResponseMessage response) =>
-        response.GetCreatedId<string>();
-
-    public static bool TryGetETagValue<T>(this HttpResponseMessage response, out T? value)
-    {
-        value = default;
-
-        var eTagHeader = response.Headers.ETag?.Tag;
-
-        if (string.IsNullOrEmpty(eTagHeader))
-            return false;
-
-        eTagHeader = eTagHeader.Substring(1, eTagHeader.Length - 2);
-
-        var result = TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(eTagHeader);
-
-        if (result == null)
-            return false;
-
-        value = (T?)result;
-
-        return true;
-    }
-
-    public static T GetETagValue<T>(this HttpResponseMessage response) =>
-        response.TryGetCreatedId<T>(out var createdId)
-            ? createdId!
-            : throw new ArgumentOutOfRangeException(nameof(response.Headers.ETag));
-
-    public static string GetETagValue(this HttpResponseMessage response) =>
-        response.GetETagValue<string>();
-
-    public static async Task<T> GetResultFromJson<T>(this HttpResponseMessage response, JsonSerializerSettings? settings = null)
-    {
-        var result = await response.Content.ReadAsStringAsync();
-
-        result.Should().NotBeNull();
-        result.Should().NotBeEmpty();
-
-        var deserialised = result.FromJson<T>(settings);
-
-        deserialised.Should().NotBeNull();
-
-        return deserialised;
-    }
+    public static Task<HttpResponseMessage> Send(
+        this HttpClient httpClient,
+        TestApiRequest testApiRequest,
+        CancellationToken ct = default
+    ) =>
+        httpClient.SendAsync(testApiRequest.Build(), ct);
 }
diff --git a/src/Ogooreck/API/ApiSpecificationExtensions.cs b/src/Ogooreck/API/ApiSpecificationExtensions.cs
new file mode 100644
index 0000000..4c551b8
--- /dev/null
+++ b/src/Ogooreck/API/ApiSpecificationExtensions.cs
@@ -0,0 +1,321 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+using FluentAssertions;
+
+namespace Ogooreck.API;
+
+#pragma warning disable CS1591
+public static class ApiSpecification
+{
+    ///////////////////
+    ////   GIVEN   ////
+    ///////////////////
+
+    public static GivenApiSpecificationBuilder Given<TProgram>(this ApiSpecification<TProgram> api,
+        params RequestTransform[] when) where TProgram : class =>
+        api.Given(new RequestDefinition(when));
+
+
+    public static GivenApiSpecificationBuilder Given<TProgram>(this ApiSpecification<TProgram> api,
+        string description,
+        params RequestTransform[] when) where TProgram : class =>
+        api.Given(description, new RequestDefinition(when, description));
+
+    ///////////////////
+    ////   WHEN    ////
+    ///////////////////
+
+    public static RequestDefinition SEND(params RequestTransform[] when) => new(when);
+
+
+    public static RequestDefinition SEND(string description, params RequestTransform[] when) => new(when, description);
+
+    public static RequestTransform URI(Func<TestContext, string> getUrl) =>
+        URI(ctx => new Uri(getUrl(ctx), UriKind.RelativeOrAbsolute));
+
+    public static RequestTransform URI(string uri) =>
+        URI(new Uri(uri, UriKind.RelativeOrAbsolute));
+
+    public static RequestTransform URI(Uri uri) =>
+        URI(_ => uri);
+
+    public static RequestTransform URI(Func<TestContext, Uri> getUri) =>
+        (request, ctx) =>
+        {
+            request.RequestUri = getUri(ctx);
+            return request;
+        };
+
+    public static RequestTransform BODY<T>(T body) =>
+        (request, _) =>
+        {
+            request.Content = JsonContent.Create(body);
+
+            return request;
+        };
+
+    public static RequestTransform HEADERS(params Action<HttpRequestHeaders>[] headers) =>
+        (request, _) =>
+        {
+            foreach (var header in headers)
+            {
+                header(request.Headers);
+            }
+
+            return request;
+        };
+
+
+    public static RequestTransform GET =>
+        (request, _) =>
+        {
+            request.Method = HttpMethod.Get;
+            return request;
+        };
+
+    public static RequestTransform POST => SEND(HttpMethod.Post);
+
+    public static RequestTransform PUT => SEND(HttpMethod.Put);
+
+    public static RequestTransform DELETE => SEND(HttpMethod.Delete);
+
+    public static RequestTransform OPTIONS => SEND(HttpMethod.Options);
+
+    public static RequestTransform SEND(HttpMethod method) =>
+        (request, _) =>
+        {
+            request.Method = method;
+            return request;
+        };
+
+    public static Action<HttpRequestHeaders> IF_MATCH(string ifMatch, bool isWeak = true) =>
+        headers => headers.IfMatch.Add(new EntityTagHeaderValue($"\"{ifMatch}\"", isWeak));
+
+    public static Action<HttpRequestHeaders> IF_MATCH(object ifMatch, bool isWeak = true) =>
+        IF_MATCH(ifMatch.ToString()!, isWeak);
+
+    public static Task<HttpResponseMessage> And(this Task<Result> result,
+        Func<HttpResponseMessage, HttpResponseMessage> and) =>
+        result.ContinueWith(t => and(t.Result.Response));
+
+    public static Task And(this Task<Result> result, Func<HttpResponseMessage, Task> and) =>
+        result.ContinueWith(t => and(t.Result.Response));
+
+    public static Task And<TResult>(this Task<Result> result,
+        Func<HttpResponseMessage, Task<TResult>> and) =>
+        result.ContinueWith(t => and(t.Result.Response));
+
+    public static Task And(this Task<Result> result, Func<Task> and) =>
+        result.ContinueWith(_ => and());
+
+    public static Task And(this Task<Result> result, Task and) =>
+        result.ContinueWith(_ => and);
+
+    public static Task<GivenApiSpecificationBuilder> And(this Task<Result> result) =>
+        result.ContinueWith(
+            _ => new GivenApiSpecificationBuilder(result.Result.TestContext, result.Result.CreateClient));
+
+    public static Task<WhenApiSpecificationBuilder> AndWhen(
+        this Task<Result> result,
+        string description,
+        params RequestTransform[] when
+    ) =>
+        result.And().When(description, when);
+
+    public static Task<WhenApiSpecificationBuilder> AndWhen(this Task<Result> result, params RequestTransform[] when) =>
+        result.And().When(when);
+
+    public static Task<WhenApiSpecificationBuilder> AndWhen(
+        this Task<Result> result,
+        string description,
+        Func<HttpResponseMessage, RequestTransform[]> when
+    ) =>
+        result.ContinueWith(r =>
+            new GivenApiSpecificationBuilder(r.Result.TestContext, r.Result.CreateClient)
+                .When(description, when(r.Result.Response))
+        );
+
+    public static Task<WhenApiSpecificationBuilder> AndWhen(
+        this Task<Result> result,
+        Func<HttpResponseMessage, RequestTransform[]> when
+    ) =>
+        result.ContinueWith(r =>
+            new GivenApiSpecificationBuilder(r.Result.TestContext, r.Result.CreateClient).When(when(r.Result.Response))
+        );
+
+    public static Task<WhenApiSpecificationBuilder> When(
+        this Task<GivenApiSpecificationBuilder> result,
+        string description,
+        params RequestTransform[] when
+    ) =>
+        result.ContinueWith(_ => result.Result.When(description, when));
+
+    public static Task<WhenApiSpecificationBuilder> When(
+        this Task<GivenApiSpecificationBuilder> result,
+        params RequestTransform[] when
+    ) =>
+        result.ContinueWith(_ => result.Result.When(when));
+
+    public static Task<WhenApiSpecificationBuilder> Until(
+        this Task<WhenApiSpecificationBuilder> when,
+        RetryCheck check,
+        int maxNumberOfRetries = 5,
+        int retryIntervalInMs = 1000
+    ) =>
+        when.ContinueWith(t => t.Result.Until(check, maxNumberOfRetries, retryIntervalInMs));
+
+    public static Task<Result> Then(
+        this Task<WhenApiSpecificationBuilder> when,
+        ResponseAssert then
+    ) =>
+        when.ContinueWith(t => t.Result.Then(then)).Unwrap();
+
+    public static Task<Result> Then(
+        this Task<WhenApiSpecificationBuilder> when,
+        params ResponseAssert[] thens
+    ) =>
+        when.ContinueWith(t => t.Result.Then(thens)).Unwrap();
+
+    public static Task<Result> Then(
+        this Task<WhenApiSpecificationBuilder> when,
+        IEnumerable<ResponseAssert> thens,
+        CancellationToken ct
+    ) =>
+        when.ContinueWith(t => t.Result.Then(thens, ct), ct).Unwrap();
+
+
+    public static Task<T> GetResponseBody<T>(this Task<Result> result) => result.Map(RESPONSE_BODY<T>());
+    public static Task<T> GetCreatedId<T>(this Task<Result> result) => result.Map(CREATED_ID<T>());
+
+    public static Task<T> Map<T>(
+        this Task<Result> result,
+        Func<HttpResponseMessage, Task<T>> map
+    ) =>
+        result.ContinueWith(t => map(t.Result.Response)).Unwrap();
+
+    ///////////////////
+    ////   THEN    ////
+    ///////////////////
+    public static ResponseAssert OK = HTTP_STATUS(HttpStatusCode.OK);
+    public static ResponseAssert CREATED = HTTP_STATUS(HttpStatusCode.Created);
+    public static ResponseAssert NO_CONTENT = HTTP_STATUS(HttpStatusCode.NoContent);
+    public static ResponseAssert BAD_REQUEST = HTTP_STATUS(HttpStatusCode.BadRequest);
+    public static ResponseAssert NOT_FOUND = HTTP_STATUS(HttpStatusCode.NotFound);
+    public static ResponseAssert CONFLICT = HTTP_STATUS(HttpStatusCode.Conflict);
+
+    public static ResponseAssert PRECONDITION_FAILED =
+        HTTP_STATUS(HttpStatusCode.PreconditionFailed);
+
+    public static ResponseAssert METHOD_NOT_ALLOWED =
+        HTTP_STATUS(HttpStatusCode.MethodNotAllowed);
+
+    public static ResponseAssert HTTP_STATUS(HttpStatusCode status) =>
+        (response, ctx) =>
+        {
+            response.StatusCode.Should().Be(status);
+            return ValueTask.CompletedTask;
+        };
+
+    public static ResponseAssert CREATED_WITH_DEFAULT_HEADERS(
+        string? locationHeaderPrefix = null, object? eTag = null, bool isETagWeak = true) =>
+        async (response, ctx) =>
+        {
+            await CREATED(response, ctx);
+            await RESPONSE_LOCATION_HEADER(locationHeaderPrefix)(response, ctx);
+            if (eTag != null)
+                await RESPONSE_ETAG_HEADER(eTag, isETagWeak)(response, ctx);
+        };
+
+    public static ResponseAssert RESPONSE_BODY<T>(T body) =>
+        RESPONSE_BODY<T>(result => result.Should().BeEquivalentTo(body));
+
+    public static ResponseAssert RESPONSE_BODY<T>(Func<TestContext, T> getBody) =>
+        RESPONSE_BODY<T>((result, ctx) => result.Should().BeEquivalentTo(getBody(ctx)));
+
+    public static ResponseAssert RESPONSE_BODY<T>(Action<T> assert) =>
+        RESPONSE_BODY<T>((body, _) => assert(body));
+
+    public static ResponseAssert RESPONSE_BODY<T>(Action<T, TestContext> assert) =>
+        async (response, ctx) =>
+        {
+            var result = await response.GetResultFromJson<T>();
+            assert(result, ctx);
+
+            result.Should().BeEquivalentTo(result);
+        };
+
+    public static Func<HttpResponseMessage, Task<T>> RESPONSE_BODY<T>() =>
+        response => response.GetResultFromJson<T>();
+
+    public static Func<HttpResponseMessage, Task<T>> CREATED_ID<T>() =>
+        response => Task.FromResult(response.GetCreatedId<T>());
+
+    public static ResponseAssert RESPONSE_ETAG_HEADER(object eTag, bool isWeak = true) =>
+        RESPONSE_HEADERS(headers =>
+        {
+            headers.ETag.Should().NotBeNull("ETag response header should be defined").And
+                .NotBe("", "ETag response header should not be empty");
+            headers.ETag!.Tag.Should().NotBeEmpty("ETag response header should not be empty");
+
+            headers.ETag.IsWeak.Should().Be(isWeak, "Etag response header should be {0}", isWeak ? "Weak" : "Strong");
+            headers.ETag.Tag.Should().Be($"\"{eTag}\"");
+        });
+
+    public static ResponseAssert RESPONSE_LOCATION_HEADER(string? locationHeaderPrefix = null) =>
+        async (response, ctx) =>
+        {
+            await HTTP_STATUS(HttpStatusCode.Created)(response, ctx);
+
+            var locationHeader = response.Headers.Location;
+
+            locationHeader.Should().NotBeNull();
+
+            var location = locationHeader!.ToString();
+
+            location.Should().StartWith(locationHeaderPrefix ?? response.RequestMessage!.RequestUri!.AbsolutePath);
+        };
+
+    public static ResponseAssert RESPONSE_HEADERS(params Action<HttpResponseHeaders>[] headers) =>
+        (response, ctx) =>
+        {
+            foreach (var header in headers)
+            {
+                header(response.Headers);
+            }
+
+            return ValueTask.CompletedTask;
+        };
+
+    /////////////////
+    //     UNTIL
+    ////////////////
+
+    public static RetryCheck RESPONSE_ETAG_IS(object eTag,
+        bool isWeak = true) =>
+        async (response, ctx) =>
+        {
+            await RESPONSE_ETAG_HEADER(eTag, isWeak)(response, ctx);
+            return true;
+        };
+
+    public static RetryCheck RESPONSE_SUCCEEDED() =>
+        (response, ctx) =>
+        {
+            response.EnsureSuccessStatusCode();
+            return new ValueTask<bool>(true);
+        };
+
+    public static RetryCheck RESPONSE_BODY_MATCHES<TBody>(Func<TBody, bool> assert) =>
+        async (response, ctx) =>
+        {
+            response.EnsureSuccessStatusCode();
+
+            var result = await response.GetResultFromJson<TBody>();
+            result.Should().NotBeNull();
+
+            return assert(result);
+        };
+
+    public record Result(HttpResponseMessage Response, TestContext TestContext, Func<HttpClient> CreateClient);
+}
diff --git a/src/Ogooreck/API/HttpResponseMessageExtensions.cs b/src/Ogooreck/API/HttpResponseMessageExtensions.cs
new file mode 100644
index 0000000..241249c
--- /dev/null
+++ b/src/Ogooreck/API/HttpResponseMessageExtensions.cs
@@ -0,0 +1,96 @@
+using System.ComponentModel;
+using FluentAssertions;
+using Newtonsoft.Json;
+using Ogooreck.Newtonsoft;
+
+namespace Ogooreck.API;
+
+#pragma warning disable CS1591
+public static class HttpResponseMessageExtensions
+{
+    public static bool TryGetCreatedId<T>(this HttpResponseMessage response, out T? value)
+    {
+        value = default;
+
+        var locationHeader = response.Headers.Location?.OriginalString.TrimEnd('/');
+
+        if (string.IsNullOrEmpty(locationHeader))
+            return false;
+
+        locationHeader = locationHeader.StartsWith("/") ? locationHeader : $"/{locationHeader}";
+
+        var start = locationHeader.LastIndexOf("/", locationHeader.Length - 1, StringComparison.Ordinal);
+
+        var createdId = locationHeader.Substring(start + 1, locationHeader.Length - 1 - start);
+
+        var result = TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(createdId);
+
+        if (result == null)
+            return false;
+
+        value = (T?)result;
+
+        return true;
+    }
+
+    public static T GetCreatedId<T>(this HttpResponseMessage response) =>
+        response.TryGetCreatedId<T>(out var createdId)
+            ? createdId!
+            : throw new ArgumentOutOfRangeException(nameof(response.Headers.Location));
+
+    public static string GetCreatedId(this HttpResponseMessage response) =>
+        response.GetCreatedId<string>();
+
+    public static bool TryGetETagValue<T>(this HttpResponseMessage response, out T? value)
+    {
+        value = default;
+
+        var eTagHeader = response.Headers.ETag?.Tag;
+
+        if (string.IsNullOrEmpty(eTagHeader))
+            return false;
+
+        eTagHeader = eTagHeader.Substring(1, eTagHeader.Length - 2);
+
+        var result = TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(eTagHeader);
+
+        if (result == null)
+            return false;
+
+        value = (T?)result;
+
+        return true;
+    }
+
+    public static T GetETagValue<T>(this HttpResponseMessage response) =>
+        response.TryGetCreatedId<T>(out var createdId)
+            ? createdId!
+            : throw new ArgumentOutOfRangeException(nameof(response.Headers.ETag));
+
+    public static string GetETagValue(this HttpResponseMessage response) =>
+        response.GetETagValue<string>();
+
+    public static Task<T> GetResultFromJson<T>(
+        this ApiSpecification.Result result,
+        JsonSerializerSettings? settings = null
+    ) =>
+        result.Response.GetResultFromJson<T>();
+
+
+    public static async Task<T> GetResultFromJson<T>(
+        this HttpResponseMessage response,
+        JsonSerializerSettings? settings = null
+    )
+    {
+        var result = await response.Content.ReadAsStringAsync();
+
+        result.Should().NotBeNull();
+        result.Should().NotBeEmpty();
+
+        var deserialised = result.FromJson<T>(settings);
+
+        deserialised.Should().NotBeNull();
+
+        return deserialised;
+    }
+}
diff --git a/src/Ogooreck/API/RetryPolicy.cs b/src/Ogooreck/API/RetryPolicy.cs
new file mode 100644
index 0000000..65b7bca
--- /dev/null
+++ b/src/Ogooreck/API/RetryPolicy.cs
@@ -0,0 +1,49 @@
+using FluentAssertions;
+
+namespace Ogooreck.API;
+
+#pragma warning disable CS1591
+public record RetryPolicy(
+    RetryCheck Check,
+    int MaxNumberOfRetries = 5,
+    int RetryIntervalInMs = 1000
+)
+{
+    public async Task<HttpResponseMessage> Perform(Func<CancellationToken, Task<HttpResponseMessage>> send, TestContext testContext, CancellationToken ct)
+    {
+        var retryCount = MaxNumberOfRetries;
+        var finished = false;
+
+        HttpResponseMessage? response = null;
+        do
+        {
+            try
+            {
+                response = await send(ct);
+
+                finished = await Check(response, testContext);
+            }
+            catch
+            {
+                if (retryCount == 0)
+                    throw;
+            }
+
+            await Task.Delay(RetryIntervalInMs, ct);
+            retryCount--;
+        } while (!finished);
+
+        response.Should().NotBeNull();
+
+        return response!;
+    }
+
+    public static readonly RetryPolicy NoRetry = new RetryPolicy(
+        (r, t) => ValueTask.FromResult(true),
+        0,
+        0
+    );
+}
+
+public delegate ValueTask<bool> RetryCheck(HttpResponseMessage responseMessage, TestContext testContext);
+
diff --git a/src/Ogooreck/API/TestBuilders.cs b/src/Ogooreck/API/TestBuilders.cs
new file mode 100644
index 0000000..1795032
--- /dev/null
+++ b/src/Ogooreck/API/TestBuilders.cs
@@ -0,0 +1,155 @@
+using System.Net;
+
+namespace Ogooreck.API;
+
+#pragma warning disable CS1591
+
+public class GivenApiSpecificationBuilder
+{
+    private readonly ApiTestStep[] given;
+    private readonly Func<HttpClient> createClient;
+    private readonly TestContext testContext;
+
+    internal GivenApiSpecificationBuilder
+    (
+        TestContext testContext,
+        Func<HttpClient> createClient,
+        ApiTestStep[] given
+    )
+    {
+        this.testContext = testContext;
+        this.createClient = createClient;
+        this.given = given;
+    }
+
+    internal GivenApiSpecificationBuilder
+    (
+        TestContext testContext,
+        Func<HttpClient> createClient
+    ): this(testContext, createClient, Array.Empty<ApiTestStep>())
+    {
+    }
+
+    public WhenApiSpecificationBuilder When(params RequestTransform[] when) =>
+        When("", when);
+
+    public WhenApiSpecificationBuilder When(string description, params RequestTransform[] when) =>
+        When("", new RequestDefinition(when, description));
+
+    public WhenApiSpecificationBuilder When(RequestDefinition when) => When(when.Description, when);
+
+    public WhenApiSpecificationBuilder When(string description, RequestDefinition when) =>
+        new(
+            createClient,
+            testContext,
+            given,
+            new ApiTestStep(TestPhase.When, when, description)
+        );
+}
+
+public class WhenApiSpecificationBuilder
+{
+    private readonly ApiTestStep[] given;
+    private readonly ApiTestStep when;
+    private readonly Func<HttpClient> createClient;
+    private readonly TestContext testContext;
+    private RetryPolicy retryPolicy;
+
+    internal WhenApiSpecificationBuilder(
+        Func<HttpClient> createClient,
+        TestContext testContext,
+        ApiTestStep[] given,
+        ApiTestStep when
+    )
+    {
+        this.createClient = createClient;
+        this.testContext = testContext;
+        this.given = given;
+        this.when = when;
+        retryPolicy = RetryPolicy.NoRetry;
+    }
+
+    public WhenApiSpecificationBuilder Until(
+        RetryCheck check,
+        int maxNumberOfRetries = 5,
+        int retryIntervalInMs = 1000
+    )
+    {
+        retryPolicy = new RetryPolicy(check, maxNumberOfRetries, retryIntervalInMs);
+        return this;
+    }
+
+    public Task<ApiSpecification.Result> Then(ResponseAssert then) =>
+        Then(new[] { then });
+
+    public Task<ApiSpecification.Result> Then(params ResponseAssert[] thens) =>
+        Then(thens, default);
+
+    public async Task<ApiSpecification.Result> Then(IEnumerable<ResponseAssert> thens,
+        CancellationToken ct)
+    {
+        using var client = createClient();
+
+        // Given
+        foreach (var givenBuilder in given)
+            await Send(client, RetryPolicy.NoRetry, givenBuilder, testContext, ct);
+
+        // When
+        var response = await Send(client, retryPolicy, when, testContext, ct);
+
+        // Then
+        foreach (var then in thens)
+        {
+            await then(response, testContext);
+        }
+
+        return new ApiSpecification.Result(response, testContext, createClient);
+    }
+
+    private static Task<HttpResponseMessage> Send(
+        HttpClient client,
+        RetryPolicy retryPolicy,
+        ApiTestStep testStep,
+        TestContext testContext,
+        CancellationToken ct
+    ) =>
+        retryPolicy
+            .Perform(async t =>
+            {
+                var request = TestApiRequest.For(testContext, testStep.RequestDefinition);
+                var response = await client.SendAsync(request, t);
+
+                testContext.Record(testStep, request, response);
+
+                return response;
+            }, testContext, ct);
+}
+
+public enum TestPhase
+{
+    Given,
+    When,
+    Then
+}
+
+public record RequestDefinition(RequestTransform[] Transformations, string Description = "");
+
+public record ApiTestStep(TestPhase Phase, RequestDefinition RequestDefinition, string Description = "");
+
+public record MadeApiCall(TestPhase TestPhase, HttpRequestMessage Request, HttpResponseMessage Response,
+    string Description = "");
+
+public class TestContext
+{
+    public List<MadeApiCall> Calls { get; } = new();
+
+    public void Record(ApiTestStep testStep, HttpRequestMessage request, HttpResponseMessage response) =>
+        Calls.Add(new MadeApiCall(testStep.Phase, request, response, testStep.RequestDefinition.Description));
+
+
+    public string GetCreatedId() =>
+        Calls.First(c => c.Response.StatusCode == HttpStatusCode.Created).Response.GetCreatedId();
+
+    public T GetCreatedId<T>() where T : notnull =>
+        Calls.First(c => c.Response.StatusCode == HttpStatusCode.Created).Response.GetCreatedId<T>();
+}
diff --git a/src/Ogooreck/Ogooreck.csproj b/src/Ogooreck/Ogooreck.csproj
index ab3dd9d..fff796c 100644
--- a/src/Ogooreck/Ogooreck.csproj
+++ b/src/Ogooreck/Ogooreck.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <VersionPrefix>0.7.0</VersionPrefix>
+        <VersionPrefix>0.8.0</VersionPrefix>
         <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
         <GenerateAssemblyTitleAttribute>true</GenerateAssemblyTitleAttribute>
         <GenerateAssemblyDescriptionAttribute>true</GenerateAssemblyDescriptionAttribute>