diff --git a/src/jsonschema/CMakeLists.txt b/src/jsonschema/CMakeLists.txt
index 8de677a11..068c9aa09 100644
--- a/src/jsonschema/CMakeLists.txt
+++ b/src/jsonschema/CMakeLists.txt
@@ -7,7 +7,8 @@ noa_library(NAMESPACE sourcemeta PROJECT jsontoolkit NAME jsonschema
   PRIVATE_HEADERS anchor.h bundle.h resolver.h
     walker.h reference.h frame.h error.h unevaluated.h keywords.h
   SOURCES jsonschema.cc default_walker.cc frame.cc
-    anchor.cc resolver.cc walker.cc bundle.cc unevaluated.cc
+    anchor.cc resolver.cc walker.cc bundle.cc
+    unevaluated.cc relativize.cc
     "${CMAKE_CURRENT_BINARY_DIR}/official_resolver.cc")
 
 if(JSONTOOLKIT_INSTALL)
diff --git a/src/jsonschema/include/sourcemeta/jsontoolkit/jsonschema.h b/src/jsonschema/include/sourcemeta/jsontoolkit/jsonschema.h
index 3f18f1648..a3fd5f3e8 100644
--- a/src/jsonschema/include/sourcemeta/jsontoolkit/jsonschema.h
+++ b/src/jsonschema/include/sourcemeta/jsontoolkit/jsonschema.h
@@ -322,6 +322,42 @@ SOURCEMETA_JSONTOOLKIT_JSONSCHEMA_EXPORT
 auto schema_format_compare(const JSON::String &left, const JSON::String &right)
     -> bool;
 
+/// @ingroup jsonschema
+///
+/// Try to turn every possible absolute reference in a schema into a relative
+/// one. For example:
+///
+/// ```cpp
+/// #include <sourcemeta/jsontoolkit/json.h>
+/// #include <sourcemeta/jsontoolkit/jsonschema.h>
+/// #include <cassert>
+///
+/// sourcemeta::jsontoolkit::JSON document =
+///   sourcemeta::jsontoolkit::parse(R"JSON({
+///   "$id": "https://www.example.com/schema",
+///   "$schema": "https://json-schema.org/draft/2020-12/schema",
+///   "$ref": "https://www.example.com/another",
+/// })JSON");
+///
+/// sourcemeta::jsontoolkit::relativize(schema,
+///   sourcemeta::jsontoolkit::default_dialect,
+///   sourcemeta::jsontoolkit::official_resolver);
+///
+/// const sourcemeta::jsontoolkit::JSON expected =
+///   sourcemeta::jsontoolkit::parse(R"JSON({
+///   "$id": "https://www.example.com/schema",
+///   "$schema": "https://json-schema.org/draft/2020-12/schema",
+///   "$ref": "another",
+/// })JSON");
+///
+/// assert(document == expected);
+/// ```
+SOURCEMETA_JSONTOOLKIT_JSONSCHEMA_EXPORT
+auto relativize(
+    JSON &schema, const SchemaWalker &walker, const SchemaResolver &resolver,
+    const std::optional<std::string> &default_dialect = std::nullopt,
+    const std::optional<std::string> &default_id = std::nullopt) -> void;
+
 } // namespace sourcemeta::jsontoolkit
 
 #endif
diff --git a/src/jsonschema/relativize.cc b/src/jsonschema/relativize.cc
new file mode 100644
index 000000000..664c39817
--- /dev/null
+++ b/src/jsonschema/relativize.cc
@@ -0,0 +1,43 @@
+#include <sourcemeta/jsontoolkit/jsonschema.h>
+
+namespace sourcemeta::jsontoolkit {
+
+auto relativize(JSON &schema, const SchemaWalker &walker,
+                const SchemaResolver &resolver,
+                const std::optional<std::string> &default_dialect,
+                const std::optional<std::string> &default_id) -> void {
+  Frame frame;
+  frame.analyse(schema, walker, resolver, default_dialect, default_id);
+
+  for (const auto &entry : frame.locations()) {
+    if (entry.second.type != Frame::LocationType::Resource &&
+        entry.second.type != Frame::LocationType::Subschema) {
+      continue;
+    }
+
+    auto &subschema{get(schema, entry.second.pointer)};
+    assert(is_schema(subschema));
+    if (!subschema.is_object()) {
+      continue;
+    }
+
+    const auto base{URI{entry.second.base}.canonicalize()};
+    for (const auto &property : subschema.as_object()) {
+      if (walker(property.first, frame.vocabularies(entry.second, resolver))
+                  .type != KeywordType::Reference ||
+          !property.second.is_string()) {
+        continue;
+      }
+
+      URI reference{property.second.to_string()};
+      reference.canonicalize();
+      reference.relative_to(base);
+
+      if (reference.is_relative()) {
+        subschema.assign(property.first, JSON{reference.recompose()});
+      }
+    }
+  }
+}
+
+} // namespace sourcemeta::jsontoolkit
diff --git a/test/jsonschema/CMakeLists.txt b/test/jsonschema/CMakeLists.txt
index 88ed38e91..c36e83754 100644
--- a/test/jsonschema/CMakeLists.txt
+++ b/test/jsonschema/CMakeLists.txt
@@ -83,6 +83,7 @@ add_executable(sourcemeta_jsontoolkit_jsonschema_unit
   jsonschema_error_test.cc
   jsonschema_keyword_iterator_test.cc
   jsonschema_official_resolver_test.cc
+  jsonschema_relativize_test.cc
   jsonschema_map_resolver_test.cc
   jsonschema_flat_file_resolver_test.cc
   jsonschema_format_test.cc)
diff --git a/test/jsonschema/jsonschema_relativize_test.cc b/test/jsonschema/jsonschema_relativize_test.cc
new file mode 100644
index 000000000..d19406c6b
--- /dev/null
+++ b/test/jsonschema/jsonschema_relativize_test.cc
@@ -0,0 +1,298 @@
+#include <gtest/gtest.h>
+
+#include <sourcemeta/jsontoolkit/json.h>
+#include <sourcemeta/jsontoolkit/jsonschema.h>
+
+TEST(JSONSchema_relativize, draft4_1) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://asyncapi.com/definitions/1.0.0/asyncapi.json",
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "title": "AsyncAPI 1.0 schema.",
+    "type": "object",
+    "required": [
+        "asyncapi",
+        "info",
+        "topics"
+    ],
+    "additionalProperties": false,
+    "patternProperties": {
+        "^x-": {
+            "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+        }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver);
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://asyncapi.com/definitions/1.0.0/asyncapi.json",
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "title": "AsyncAPI 1.0 schema.",
+    "type": "object",
+    "required": [
+        "asyncapi",
+        "info",
+        "topics"
+    ],
+    "additionalProperties": false,
+    "patternProperties": {
+        "^x-": {
+            "$ref": "vendorExtension.json"
+        }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_2) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://example.com",
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver);
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://example.com",
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_3) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://example.com",
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://example.com/nested"
+      },
+      "bar": {
+        "id": "http://sourcemeta.com",
+        "properties": {
+          "bar": {
+            "$ref": "http://example.com/nested"
+          },
+          "baz": {
+            "$ref": "http://sourcemeta.com/nested"
+          }
+        }
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver);
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://example.com",
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "nested"
+      },
+      "bar": {
+        "id": "http://sourcemeta.com",
+        "properties": {
+          "bar": {
+            "$ref": "http://example.com/nested"
+          },
+          "baz": {
+            "$ref": "nested"
+          }
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_4) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver);
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_5) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://example.com/nested"
+      },
+      "bar": {
+        "id": "http://sourcemeta.com",
+        "properties": {
+          "bar": {
+            "$ref": "http://example.com/nested"
+          },
+          "baz": {
+            "$ref": "http://sourcemeta.com/nested"
+          }
+        }
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver);
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://example.com/nested"
+      },
+      "bar": {
+        "id": "http://sourcemeta.com",
+        "properties": {
+          "bar": {
+            "$ref": "http://example.com/nested"
+          },
+          "baz": {
+            "$ref": "nested"
+          }
+        }
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_6) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver, std::nullopt,
+      "http://asyncapi.com/definitions");
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema",
+    "properties": {
+      "foo": {
+        "$ref": "1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_7) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://asyncapi.com/definitions",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver,
+      "http://json-schema.org/draft-04/schema");
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://asyncapi.com/definitions",
+    "properties": {
+      "foo": {
+        "$ref": "1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}
+
+TEST(JSONSchema_relativize, draft4_8) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "id": "http://asyncapi.com/definitions",
+    "properties": {
+      "foo": {
+        "$ref": "http://asyncapi.com/definitions/1.0.0/vendorExtension.json"
+      }
+    }
+  })JSON");
+
+  EXPECT_THROW(sourcemeta::jsontoolkit::relativize(
+                   schema, sourcemeta::jsontoolkit::default_schema_walker,
+                   sourcemeta::jsontoolkit::official_resolver),
+               sourcemeta::jsontoolkit::SchemaError);
+}
+
+TEST(JSONSchema_relativize, 2020_12_1) {
+  auto schema = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$id": "http://example.com",
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "properties": {
+      "foo": {
+        "$dynamicRef": "http://example.com/foo#bar"
+      }
+    }
+  })JSON");
+
+  sourcemeta::jsontoolkit::relativize(
+      schema, sourcemeta::jsontoolkit::default_schema_walker,
+      sourcemeta::jsontoolkit::official_resolver);
+
+  const auto expected = sourcemeta::jsontoolkit::parse(R"JSON({
+    "$id": "http://example.com",
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "properties": {
+      "foo": {
+        "$dynamicRef": "foo#bar"
+      }
+    }
+  })JSON");
+
+  EXPECT_EQ(schema, expected);
+}