diff --git a/pom.xml b/pom.xml
index 3d156c5..4a4b12d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -51,6 +51,10 @@
       <groupId>io.quarkus</groupId>
       <artifactId>quarkus-rest</artifactId>
     </dependency>
+    <dependency>
+      <groupId>io.quarkus</groupId>
+      <artifactId>quarkus-hibernate-validator</artifactId>
+    </dependency>
     <dependency>
       <groupId>io.quarkus</groupId>
       <artifactId>quarkus-junit</artifactId>
diff --git a/src/main/java/de/schulung/quarkus/recipes/Ingredient.java b/src/main/java/de/schulung/quarkus/recipes/Ingredient.java
index 39c75a3..27c6189 100644
--- a/src/main/java/de/schulung/quarkus/recipes/Ingredient.java
+++ b/src/main/java/de/schulung/quarkus/recipes/Ingredient.java
@@ -1,5 +1,9 @@
 package de.schulung.quarkus.recipes;
 
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import jakarta.validation.constraints.Size;
+
 import lombok.Getter;
 import lombok.Setter;
 
@@ -10,14 +14,18 @@ public class Ingredient {
   /**
    * The ingredient name.
    */
+  @NotNull
+  @Size(min = 1, max = 100)
   private String name;
   /**
    * The quantity of the ingredient.
    */
+  @Positive
   private double quantity;
   /**
    * The unit of the ingredient.
    */
+  @NotNull
   private IngredientUnit unit;
 
 }
diff --git a/src/main/java/de/schulung/quarkus/recipes/Recipe.java b/src/main/java/de/schulung/quarkus/recipes/Recipe.java
index af6da5d..13058d3 100644
--- a/src/main/java/de/schulung/quarkus/recipes/Recipe.java
+++ b/src/main/java/de/schulung/quarkus/recipes/Recipe.java
@@ -1,7 +1,11 @@
 package de.schulung.quarkus.recipes;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
-
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Pattern;
+import jakarta.validation.constraints.Size;
 import lombok.Getter;
 import lombok.Setter;
 
@@ -20,14 +24,19 @@ public class Recipe {
   /**
    * The recipe name.
    */
+  @NotNull
+  @Size(min = 1, max = 100)
   private String name;
   /**
    * URL of the recipe image, absolute or relative.
    */
+  @Size(max = 255)
+  @Pattern(regexp = "^(/|https?://).+")
   private String img;
   /**
    * The number of servings.
    */
+  @Min(1)
   private int servings;
   /**
    * The last edited timestamp (read-only, assigned by the server).
@@ -37,6 +46,7 @@ public class Recipe {
   /**
    * Preparation time in minutes.
    */
+  @Min(1)
   private int duration;
   /**
    * Difficulty level of the recipe.
@@ -45,10 +55,14 @@ public class Recipe {
   /**
    * List of ingredients.
    */
-  private List<Ingredient> ingredients;
+  @NotNull
+  @Size(max = 100)
+  private List<@Valid @NotNull Ingredient> ingredients;
   /**
    * Preparation instructions.
    */
+  @NotNull
+  @Size(max = 2000)
   private String preparation;
 
 }
diff --git a/src/main/java/de/schulung/quarkus/recipes/RecipesResource.java b/src/main/java/de/schulung/quarkus/recipes/RecipesResource.java
index 66e02fd..aa71ffe 100644
--- a/src/main/java/de/schulung/quarkus/recipes/RecipesResource.java
+++ b/src/main/java/de/schulung/quarkus/recipes/RecipesResource.java
@@ -1,5 +1,6 @@
 package de.schulung.quarkus.recipes;
 
+import jakarta.validation.Valid;
 import jakarta.ws.rs.*;
 import jakarta.ws.rs.core.Context;
 import jakarta.ws.rs.core.MediaType;
@@ -26,6 +27,7 @@ public Collection<Recipe> getAllRecipes() {
 
   @POST
   public Response createRecipe(
+    @Valid
     Recipe recipe,
     @Context
     UriInfo uriInfo
diff --git a/src/test/java/de/schulung/quarkus/recipes/RecipesResourceTests.java b/src/test/java/de/schulung/quarkus/recipes/RecipesResourceTests.java
index 9c71c0d..b75a3f6 100644
--- a/src/test/java/de/schulung/quarkus/recipes/RecipesResourceTests.java
+++ b/src/test/java/de/schulung/quarkus/recipes/RecipesResourceTests.java
@@ -238,6 +238,7 @@ void shouldApplyDefaultDifficultyWhenNotProvided() {
 
   static Stream<Arguments> invalidRecipeRequests() {
     return Stream.of(
+      // --- unknown / read-only properties ---
       Arguments.of(
         "unknown property",
         """
@@ -286,6 +287,326 @@ static Stream<Arguments> invalidRecipeRequests() {
             "preparation": "Cook it."
           }
           """
+      ),
+      // --- Recipe: name (required, minLength 1, maxLength 100) ---
+      Arguments.of(
+        "missing name",
+        """
+          {
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "empty name",
+        """
+          {
+            "name": "",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "name too long",
+        """
+          {
+            "name": "%s",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """.formatted("A".repeat(101))
+      ),
+      // --- Recipe: img (maxLength 255, pattern ^(/|https?://).+) ---
+      Arguments.of(
+        "img invalid pattern",
+        """
+          {
+            "name": "Test Recipe",
+            "img": "not-a-valid-url",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "img too long",
+        """
+          {
+            "name": "Test Recipe",
+            "img": "/%s",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """.formatted("a".repeat(255))
+      ),
+      // --- Recipe: servings (required, minimum 1) ---
+      Arguments.of(
+        "missing servings",
+        """
+          {
+            "name": "Test Recipe",
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "servings zero",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 0,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      // --- Recipe: duration (required, minimum 1) ---
+      Arguments.of(
+        "missing duration",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "duration zero",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 0,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      // --- Recipe: difficulty (enum: easy, medium, hard) ---
+      Arguments.of(
+        "invalid difficulty",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "impossible",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      // --- Recipe: ingredients (required) ---
+      Arguments.of(
+        "missing ingredients",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      // --- Recipe: preparation (required, maxLength 2000) ---
+      Arguments.of(
+        "missing preparation",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ]
+          }
+          """
+      ),
+      Arguments.of(
+        "preparation too long",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "%s"
+          }
+          """.formatted("A".repeat(2001))
+      ),
+      // --- Ingredient: unit (required, enum) ---
+      Arguments.of(
+        "ingredient: missing unit",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "ingredient: invalid unit",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "bushels", "quantity": 2.0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      // --- Ingredient: quantity (required, exclusiveMinimum 0) ---
+      Arguments.of(
+        "ingredient: missing quantity",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "ingredient: quantity zero",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 0, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "ingredient: quantity negative",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": -1, "name": "Tomato"}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      // --- Ingredient: name (required, minLength 1, maxLength 100) ---
+      Arguments.of(
+        "ingredient: missing name",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "ingredient: empty name",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": ""}
+            ],
+            "preparation": "Cook it."
+          }
+          """
+      ),
+      Arguments.of(
+        "ingredient: name too long",
+        """
+          {
+            "name": "Test Recipe",
+            "servings": 4,
+            "duration": 30,
+            "difficulty": "easy",
+            "ingredients": [
+              {"unit": "pieces", "quantity": 2.0, "name": "%s"}
+            ],
+            "preparation": "Cook it."
+          }
+          """.formatted("A".repeat(101))
       )
     );
   }