diff --git a/backend/pom.xml b/backend/pom.xml
index 7abf8a1..ed6dde8 100644
--- a/backend/pom.xml
+++ b/backend/pom.xml
@@ -46,6 +46,15 @@
 			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-validation</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+			<optional>true</optional>
+		</dependency>
 	</dependencies>
 
 	<build>
diff --git a/backend/src/main/java/com/inventory/backend/controller/ProductController.java b/backend/src/main/java/com/inventory/backend/controller/ProductController.java
new file mode 100644
index 0000000..f13502e
--- /dev/null
+++ b/backend/src/main/java/com/inventory/backend/controller/ProductController.java
@@ -0,0 +1,84 @@
+package com.inventory.backend.controller;
+
+import com.inventory.backend.dto.ProductDTO;
+import com.inventory.backend.model.InventoryMetrics;
+import com.inventory.backend.model.Product;
+import com.inventory.backend.service.ProductService;
+import jakarta.validation.Valid;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.*;
+
+@RestController
+@RequestMapping("/products")
+@CrossOrigin(origins = "http://localhost:8080")
+public class ProductController {
+    private final ProductService service;
+
+    public ProductController(ProductService service) {
+        this.service = service;
+    }
+
+    // GET /products
+    @GetMapping
+    public List<Product> getProducts(
+            @RequestParam Optional<String> name,
+            @RequestParam Optional<List<String>> category,
+            @RequestParam Optional<Boolean> availability,
+            @RequestParam Optional<String> sortBy,
+            @RequestParam Optional<String> sortBy2,
+            @RequestParam(defaultValue = "true") boolean asc,
+            @RequestParam(defaultValue = "true") boolean asc2,
+            @RequestParam(defaultValue = "0") int page,
+            @RequestParam(defaultValue = "10") int size
+    ){
+        Set<String> categorySet = category.map(HashSet::new).orElse(null);
+        return service.getFilteredAndSortedProducts(
+                name,
+                Optional.ofNullable(categorySet),
+                availability,
+                sortBy,
+                sortBy2,
+                asc,
+                asc2,
+                page,
+                size
+        );
+    }
+
+    // POST /products
+    @PostMapping
+    public Product createProduct(@RequestBody @Valid ProductDTO dto) {
+        return service.createProduct(dto);
+    }
+
+    // PUT /products/{id}
+    @PutMapping("/{id}")
+    public Product updateProduct(@PathVariable UUID id, @RequestBody @Valid ProductDTO dto) {
+        return service.updateProduct(id,dto);
+    }
+
+    // DELETE /products/{id}
+    @DeleteMapping("/{id}")
+    public void deleteProduct(@PathVariable UUID id) {
+        service.deleteProduct(id);
+    }
+
+    // POST /products/{id}/outofstock
+    @PostMapping("/{id}/outofstock")
+    public void markOutOfStock(@PathVariable UUID id) {
+        service.markOutOfStock(id);
+    }
+
+    // PUT /products/{id}/instock?defaultQuantity=10
+    @PutMapping("/{id}/instock")
+    public void markInStock(@PathVariable UUID id, @RequestParam(defaultValue = "10") int defaultQuantity) {
+        service.markInStock(id, defaultQuantity);
+    }
+
+    // GET /products/metrics
+    @GetMapping("/metrics")
+    public InventoryMetrics getMetrics() {
+        return service.getMetrics();
+    }
+}
\ No newline at end of file
diff --git a/backend/src/main/java/com/inventory/backend/dto/ProductDTO.java b/backend/src/main/java/com/inventory/backend/dto/ProductDTO.java
new file mode 100644
index 0000000..fe61fc8
--- /dev/null
+++ b/backend/src/main/java/com/inventory/backend/dto/ProductDTO.java
@@ -0,0 +1,62 @@
+package com.inventory.backend.dto;
+
+import jakarta.validation.constraints.*;
+import java.time.LocalDate;
+
+public class ProductDTO {
+    @NotBlank(message = "Name is required")
+    @Size(max = 120, message = "Name must not exceed 120 characters")
+    private String name;
+
+    @NotBlank(message = "Category is required")
+    private String category;
+
+    @NotNull(message = "Unit price is required")
+    @PositiveOrZero(message = "Unit price must be 0 or more")
+    private Double unitPrice;
+
+    @PositiveOrZero(message = "Stock must be 0 or more")
+    private Integer quantityInStock;
+
+    private LocalDate expirationDate;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    public Double getUnitPrice() {
+        return unitPrice;
+    }
+
+    public void setUnitPrice(Double unitPrice) {
+        this.unitPrice = unitPrice;
+    }
+
+    public Integer getQuantityInStock() {
+        return quantityInStock;
+    }
+
+    public void setQuantityInStock(Integer quantityInStock) {
+        this.quantityInStock = quantityInStock;
+    }
+
+    public LocalDate getExpirationDate() {
+        return expirationDate;
+    }
+
+    public void setExpirationDate(LocalDate expirationDate) {
+        this.expirationDate = expirationDate;
+    }
+}
\ No newline at end of file
diff --git a/backend/src/main/java/com/inventory/backend/model/InventoryMetrics.java b/backend/src/main/java/com/inventory/backend/model/InventoryMetrics.java
new file mode 100644
index 0000000..a4c1f58
--- /dev/null
+++ b/backend/src/main/java/com/inventory/backend/model/InventoryMetrics.java
@@ -0,0 +1,124 @@
+package com.inventory.backend.model;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class InventoryMetrics {
+    private int totalInStock;
+    private double totalValue;
+    private double averagePrice;
+
+    private  Map<String, CategoryMetrics> byCategory;
+
+    public InventoryMetrics() {}
+
+    public InventoryMetrics(int totalInStock, double totalValue, double averagePrice, Map<String, CategoryMetrics> byCategory) {
+        this.totalInStock = totalInStock;
+        this.totalValue = totalValue;
+        this.averagePrice = averagePrice;
+        this.byCategory = byCategory;
+    }
+
+    public static InventoryMetrics fromProductList(List<Product> products) {
+        int totalStock = products.stream().mapToInt(Product::getQuantityInStock).sum();
+
+        double totalValue = products.stream()
+                .mapToDouble(Product::getTotalValue)
+                .sum();
+
+        List<Product> inStock = products.stream()
+                .filter(p -> p.getQuantityInStock() > 0)
+                .collect(Collectors.toList());
+
+        double averagePrice = inStock.isEmpty() ? 0:
+                inStock.stream().mapToDouble(Product::getUnitPrice).average().orElse(0);
+
+        Map<String, CategoryMetrics> categoryMetrics = products.stream()
+                .collect(Collectors.groupingBy(
+                        Product::getCategory,
+                        Collectors.collectingAndThen(Collectors.toList(), CategoryMetrics::fromProductList)
+                ));
+        return new InventoryMetrics(totalStock, totalValue, averagePrice, categoryMetrics);
+    }
+
+    public int getTotalInStock() {
+        return totalInStock;
+    }
+
+    public void setTotalInStock(int totalInStock) {
+        this.totalInStock = totalInStock;
+    }
+
+    public double getTotalValue() {
+        return totalValue;
+    }
+
+    public void setTotalValue(double totalValue) {
+        this.totalValue = totalValue;
+    }
+
+    public double getAveragePrice() {
+        return averagePrice;
+    }
+
+    public void setAveragePrice(double averagePrice) {
+        this.averagePrice = averagePrice;
+    }
+
+    public Map<String, CategoryMetrics> getByCategory() {
+        return byCategory;
+    }
+
+    public void setByCategory(Map<String, CategoryMetrics> byCategory) {
+        this.byCategory = byCategory;
+    }
+
+    public static class CategoryMetrics {
+        private  int inStock;
+        private double totalValue;
+        private double averagePrice;
+
+        public static CategoryMetrics fromProductList(List<Product> products) {
+            int stock = products.stream().mapToInt(Product::getQuantityInStock).sum();
+            double value = products.stream().mapToDouble(Product::getTotalValue).sum();
+
+            List<Product> inStock = products.stream().filter(p -> p.getQuantityInStock() > 0).toList();
+            double avg = inStock.isEmpty() ? 0 :
+                    inStock.stream().mapToDouble(Product::getUnitPrice).average().orElse(0);
+
+            return new CategoryMetrics(stock, value, avg);
+        }
+
+        public CategoryMetrics() {}
+
+        public CategoryMetrics(int inStock, double totalValue, double averagePrice) {
+            this.inStock = inStock;
+            this.totalValue = totalValue;
+            this.averagePrice = averagePrice;
+        }
+
+        public double getTotalValue() {
+            return totalValue;
+        }
+
+        public void setTotalValue(double totalValue) {
+            this.totalValue = totalValue;
+        }
+
+        public double getAveragePrice() {
+            return averagePrice;
+        }
+
+        public void setAveragePrice(double averagePrice) {
+            this.averagePrice = averagePrice;
+        }
+
+        public int getInStock() {
+            return inStock;
+        }
+
+        public void setInStock(int inStock) {
+            this.inStock = inStock;
+        }
+    }
+}
\ No newline at end of file
diff --git a/backend/src/main/java/com/inventory/backend/model/Product.java b/backend/src/main/java/com/inventory/backend/model/Product.java
index 32a9197..7695688 100644
--- a/backend/src/main/java/com/inventory/backend/model/Product.java
+++ b/backend/src/main/java/com/inventory/backend/model/Product.java
@@ -1,6 +1,5 @@
 package com.inventory.backend.model;
 
-import java.math.BigDecimal;
 import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.util.UUID;
@@ -9,9 +8,94 @@ public class Product {
     private UUID id;
     private String name;
     private String category;
-    private BigDecimal number;
-    private LocalDate expirationDate;
+    private double unitPrice;
     private int quantityInStock;
+    private LocalDate expirationDate;
     private LocalDateTime createdAt;
     private LocalDateTime updatedAt;
+
+    public Product(){}
+
+    public Product(UUID id, String name, String category, double unitPrice, int quantityInStock, LocalDate expirationDate) {
+        this.id = id;
+        this.name = name;
+        this.category = category;
+        this.unitPrice = unitPrice;
+        this.quantityInStock = quantityInStock;
+        this.expirationDate = expirationDate;
+        this.createdAt = LocalDateTime.now();
+        this.updatedAt = LocalDateTime.now();
+    }
+
+    public UUID getId() {
+        return id;
+    }
+
+    public void setId(UUID id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    public double getUnitPrice() {
+        return unitPrice;
+    }
+
+    public void setUnitPrice(double unitPrice) {
+        this.unitPrice = unitPrice;
+    }
+
+    public int getQuantityInStock() {
+        return quantityInStock;
+    }
+
+    public void setQuantityInStock(int quantityInStock) {
+        this.quantityInStock = quantityInStock;
+    }
+
+    public LocalDate getExpirationDate() {
+        return expirationDate;
+    }
+
+    public void setExpirationDate(LocalDate expirationDate) {
+        this.expirationDate = expirationDate;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(LocalDateTime createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public LocalDateTime getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(LocalDateTime updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+
+    public boolean isInStock() {
+        return  quantityInStock > 0;
+    }
+
+    public double getTotalValue() {
+        return unitPrice * quantityInStock;
+    }
 }
\ No newline at end of file
diff --git a/backend/src/main/java/com/inventory/backend/repository/ProductRepository.java b/backend/src/main/java/com/inventory/backend/repository/ProductRepository.java
new file mode 100644
index 0000000..d6ea2e2
--- /dev/null
+++ b/backend/src/main/java/com/inventory/backend/repository/ProductRepository.java
@@ -0,0 +1,49 @@
+package com.inventory.backend.repository;
+
+import com.inventory.backend.model.Product;
+import org.springframework.stereotype.Repository;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+@Repository
+public class ProductRepository {
+    private final Map<UUID, Product> products = new HashMap<>();
+
+    public List<Product> findAll(){
+        return  new ArrayList<>(products.values());
+    }
+
+    public Optional<Product> findById(UUID id) {
+        return Optional.ofNullable(products.get(id));
+    }
+
+    public Product save(Product product) {
+        products.put(product.getId(), product);
+        return product;
+    }
+
+    public void delete(UUID id) {
+        products.remove(id);
+    }
+
+    public boolean existsById(UUID id) {
+        return products.containsKey(id);
+    }
+
+    public void clear() {
+        products.clear();
+    }
+
+    public List<Product> findByNameOrCategoryOrAvailability(
+            Optional<String> nameFilter,
+            Optional<Set<String>> categoryFilter,
+            Optional<Boolean> availability
+    ) {
+        return products.values().stream()
+                .filter(p -> nameFilter.map(name -> p.getName().toLowerCase().contains(name.toLowerCase())).orElse(true))
+                .filter(p -> categoryFilter.map(categories -> categories.contains(p.category())).orElse(true))
+                .filter(p -> availability.map(avail -> avail == p.isInStock()).orElse(true))
+                .collect(Collectors.toList());
+    }
+}
\ No newline at end of file
diff --git a/backend/src/main/java/com/inventory/backend/service/ProductService.java b/backend/src/main/java/com/inventory/backend/service/ProductService.java
new file mode 100644
index 0000000..555a1f7
--- /dev/null
+++ b/backend/src/main/java/com/inventory/backend/service/ProductService.java
@@ -0,0 +1,122 @@
+package com.inventory.backend.service;
+
+import com.inventory.backend.dto.ProductDTO;
+import com.inventory.backend.model.Product;
+import com.inventory.backend.model.InventoryMetrics;
+import com.inventory.backend.repository.ProductRepository;
+import org.springframework.stereotype.Service;
+
+import java.time.LocalDateTime;
+import java.util.*;
+import  java.util.stream.Collectors;
+
+@Service
+public class ProductService {
+    private final ProductRepository repository;
+
+    public ProductService(ProductRepository repository) {
+        this.repository = repository;
+    }
+
+    public List<Product> getFilteredAndSortedProducts(
+            Optional<String> nameFilter,
+            Optional<Set<String>> categoryFilter,
+            Optional<Boolean> availability,
+            Optional<String> sortBy,
+            Optional<String> sortBy2,
+            boolean ascending,
+            boolean ascending2,
+            int page,
+            int size
+    ){
+        List<Product> filtered = repository.findByNameOrCategoryOrAvailability(nameFilter, categoryFilter,availability);
+
+        Comparator<Product> comparator = getComparator(sortBy.orElse(null), ascending);
+        if(sortBy2.isPresent()) {
+            comparator = comparator.thenComparing(getComparator(sortBy2.get(), ascending2));
+        }
+
+        return filtered.stream()
+                .sorted(comparator)
+                .skip((long) page * size)
+                .limit(size)
+                .collect(Collectors.toList());
+    }
+
+    private Comparator<Product> getComparator(String sortField, boolean ascending) {
+        Comparator<Product> comparator;
+
+        switch (sortField) {
+            case "name":
+                comparator = Comparator.comparing(Product::getName, String.CASE_INSENSITIVE_ORDER);
+                break;
+            case "category":
+                comparator = Comparator.comparing(Product::getCategory, String.CASE_INSENSITIVE_ORDER);
+                break;
+            case "unitPrice":
+                comparator = Comparator.comparingDouble(Product::getUnitPrice);
+                break;
+            case "quantityInStock":
+                comparator = Comparator.comparingInt(Product::getQuantityInStock);
+                break;
+            case "expirationDate":
+                comparator = Comparator.comparing(p -> Optional.ofNullable(p.getExpirationDate()).orElse(null),
+                        Comparator.nullsLast(Comparator.naturalOrder()));
+                break;
+            default:
+                comparator = Comparator.comparing(Product::getName);
+        }
+        return ascending ? comparator : comparator.reversed();
+    }
+
+    public Product createProduct(ProductDTO dto) {
+        Product product = new Product(
+                UUID.randomUUID(),
+                dto.getName(),
+                dto.getCategory(),
+                dto.getUnitPrice(),
+                dto.getQuantityInStock() != null ? dto.getQuantityInStock() : 0,
+                dto.getExpirationDate()
+        );
+        return repository.save(product);
+    }
+
+    public Product updateProduct(UUID id, ProductDTO dto) {
+        Product product = repository.findById(id).orElseThrow(() -> new NoSuchElementException("Product not found"));
+
+        product.setName(dto.getName());
+        product.setCategory(dto.getCategory());
+        product.setUnitPrice(dto.getUnitPrice());
+        product.setQuantityInStock(dto.getQuantityInStock());
+        product.setExpirationDate(dto.getExpirationDate());
+        product.setUpdatedAt(LocalDateTime.now());
+
+        return repository.save(product);
+    }
+
+    public void deleteProduct(UUID id) {
+        if(!repository.existsById(id)) {
+            throw new NoSuchElementException("Product not found");
+        }
+        repository.delete(id);
+    }
+
+    public void markOutOfStock(UUID id) {
+        Product product = repository.findById(id).orElseThrow(() -> new NoSuchElementException("Product not found"));
+        product.setQuantityInStock(0);
+        product.setUpdatedAt(LocalDateTime.now());
+        repository.save(product);
+    }
+
+    public void markInStock(UUID id, int defaultQuantity) {
+        Product product = repository.findById(id).orElseThrow(() -> new NoSuchElementException("Product not found"));
+        product.setQuantityInStock(defaultQuantity);
+        product.setUpdatedAt(LocalDateTime.now());
+        repository.save(product);
+    }
+
+    public InventoryMetrics getMetrics() {
+        List<Product> all = repository.findAll();
+        return InventoryMetrics.fromProductList(all);
+    }
+}
\ No newline at end of file