diff --git a/openapi/src/OpenAPI.kt b/openapi/src/OpenAPI.kt
index 1991d75..9be3d84 100644
--- a/openapi/src/OpenAPI.kt
+++ b/openapi/src/OpenAPI.kt
@@ -6,6 +6,8 @@ import io.swagger.v3.oas.annotations.Parameter
 import io.swagger.v3.oas.annotations.enums.ParameterIn
 import io.swagger.v3.oas.annotations.media.Schema.AccessMode
 import io.swagger.v3.oas.annotations.parameters.RequestBody
+import io.swagger.v3.oas.annotations.responses.ApiResponse
+import io.swagger.v3.oas.annotations.responses.ApiResponses
 import io.swagger.v3.oas.annotations.tags.Tag
 import klite.*
 import klite.RequestMethod.GET
@@ -58,7 +60,6 @@ internal fun toTags(routes: List<Route>) = routes.asSequence()
 internal fun toOperation(route: Route): Pair<String, Any> {
   val op = route.annotation<Operation>()
   val funHandler = route.handler as? FunHandler
-  val returnType = funHandler?.f?.returnType
   return (op?.method?.trimToNull() ?: route.method.name).lowercase() to mapOf(
     "operationId" to route.handler.let { (if (it is FunHandler) it.instance::class.simpleName + "." + it.f.name else it::class.simpleName) },
     "tags" to listOfNotNull(funHandler?.let { it.instance::class.annotation<Tag>()?.name ?: it.instance::class.simpleName }),
@@ -66,11 +67,8 @@ internal fun toOperation(route: Route): Pair<String, Any> {
       it.params.filter { it.source != null }.map { p -> toParameter(p, op) }
     },
     "requestBody" to toRequestBody(route, route.annotation<RequestBody>() ?: op?.requestBody),
-    "responses" to if (returnType?.classifier == Unit::class) mapOf(NoContent.value to mapOf("description" to "No content"))
-                   else mapOf(OK.value to mapOfNotNull("description" to "OK", "content" to returnType?.toJsonContent()))
-  ) + (op?.let { it.toNonEmptyValues { it.name != "method" } + mapOf(
-    "responses" to op.responses.associate { it.responseCode to it.toNonEmptyValues { it.name != "responseCode" } }.takeIf { it.isNotEmpty() }
-  ) } ?: emptyMap())
+    "responses" to toResponsesByCode(route, op, funHandler?.f?.returnType)
+  ) + (op?.let { it.toNonEmptyValues { it.name !in setOf("method", "requestBody", "responses") } } ?: emptyMap())
 }
 
 fun toParameter(p: Param, op: Operation? = null) = mapOf(
@@ -124,9 +122,20 @@ private fun toRequestBody(route: Route, annotation: RequestBody?): Map<String, A
       if (it.schema.implementation != Void::class.java) content["schema"] = it.schema.implementation.createType().toJsonSchema()
       it.mediaType to content
     }
-  requestBody.putIfAbsent("required", true)
   if (bodyParam != null) requestBody.putIfAbsent("content", bodyParam.type.toJsonContent())
-  return requestBody.takeIf { it.isNotEmpty() }
+  if (requestBody.isEmpty()) return null
+  requestBody.putIfAbsent("required", bodyParam == null || !bodyParam.isOptional)
+  return requestBody
+}
+
+private fun toResponsesByCode(route: Route, op: Operation?, returnType: KType?): Map<StatusCode, Any?> {
+  val responses = LinkedHashMap<StatusCode, Any?>()
+  if (returnType?.classifier == Unit::class) responses[NoContent] = mapOf("description" to "No content")
+  else if (op?.responses?.isEmpty() != false) responses[OK] = mapOfNotNull("description" to "OK", "content" to returnType?.toJsonContent())
+  (route.annotations.filterIsInstance<ApiResponse>() + (route.annotation<ApiResponses>()?.value ?: emptyArray()) + (op?.responses ?: emptyArray())).forEach {
+    responses[StatusCode(it.responseCode.toInt())] = it.toNonEmptyValues { it.name != "responseCode" }
+  }
+  return responses
 }
 
 private fun KType.toJsonContent() = mapOf(MimeTypes.json to mapOf("schema" to toJsonSchema()))
diff --git a/openapi/test/OpenAPITest.kt b/openapi/test/OpenAPITest.kt
index 18cd9f7..857e2a7 100644
--- a/openapi/test/OpenAPITest.kt
+++ b/openapi/test/OpenAPITest.kt
@@ -16,8 +16,11 @@ import klite.MimeTypes
 import klite.RequestMethod.GET
 import klite.RequestMethod.POST
 import klite.Route
+import klite.StatusCode.Companion.BadRequest
+import klite.StatusCode.Companion.Found
 import klite.StatusCode.Companion.NoContent
 import klite.StatusCode.Companion.OK
+import klite.StatusCode.Companion.Unauthorized
 import klite.annotations.*
 import org.junit.jupiter.api.Test
 import java.time.DayOfWeek
@@ -65,7 +68,7 @@ class OpenAPITest {
         mapOf("name" to "force", "required" to false, "in" to QUERY, "schema" to mapOf("type" to "boolean"))
       ),
       "requestBody" to null,
-      "responses" to mapOf(OK.value to mapOf("description" to "OK", "content" to mapOf(MimeTypes.json to mapOf("schema" to mapOf("type" to "null")))))
+      "responses" to mapOf(OK to mapOf("description" to "OK", "content" to mapOf(MimeTypes.json to mapOf("schema" to mapOf("type" to "null")))))
     ))
   }
 
@@ -84,29 +87,34 @@ class OpenAPITest {
     class MyRoutes {
       fun saveUser(e: HttpExchange, @PathParam userId: UUID, body: User) {}
     }
-
     expect(toOperation(Route(POST, "/x".toRegex(), handler = FunHandler(MyRoutes(), MyRoutes::saveUser)))).toEqual("post" to mapOf(
       "operationId" to "MyRoutes.saveUser",
       "tags" to listOf("MyRoutes"),
       "parameters" to listOf(
         mapOf("name" to "userId", "required" to true, "in" to PATH, "schema" to mapOf("type" to "string", "format" to "uuid"))
       ),
-      "requestBody" to mapOf("content" to userSchema),
-      "responses" to mapOf(NoContent.value to mapOf("description" to "No content"))
+      "requestBody" to mapOf("content" to userSchema, "required" to true),
+      "responses" to mapOf(NoContent to mapOf("description" to "No content"))
     ))
   }
 
   @Test fun `request body from annotation's implementation field`() {
     class MyRoutes {
       @RequestBody(description = "Application and applicant", content = [Content(mediaType = MimeTypes.json, schema = Schema(implementation = User::class))])
+      @ApiResponse(responseCode = "400", description = "Very bad request")
+      @ApiResponse(responseCode = "401", description = "Unauthorized")
       fun saveUser(e: HttpExchange): User = User("x", UUID.randomUUID())
     }
     expect(toOperation(Route(POST, "/x".toRegex(), handler = FunHandler(MyRoutes(), MyRoutes::saveUser), annotations = MyRoutes::saveUser.annotations))).toEqual("post" to mapOf(
       "operationId" to "MyRoutes.saveUser",
       "tags" to listOf("MyRoutes"),
       "parameters" to emptyList<Any>(),
-      "requestBody" to mapOf("description" to "Application and applicant", "required" to true, "content" to userSchema),
-      "responses" to mapOf(OK.value to mapOf("description" to "OK", "content" to userSchema))
+      "requestBody" to mapOf("description" to "Application and applicant", "required" to true, "content" to userSchema, "required" to true),
+      "responses" to mapOf(
+        OK to mapOf("description" to "OK", "content" to userSchema),
+        BadRequest to mapOf("description" to "Very bad request"),
+        Unauthorized to mapOf("description" to "Unauthorized"),
+      )
     ))
   }
 
@@ -116,7 +124,7 @@ class OpenAPITest {
       "tags" to emptyList<Any>(),
       "parameters" to null,
       "requestBody" to null,
-      "responses" to mapOf(OK.value to mapOf("description" to "OK"))
+      "responses" to mapOf(OK to mapOf("description" to "OK"))
     ))
   }
 
@@ -133,7 +141,7 @@ class OpenAPITest {
       "tags" to listOf("my-tag"),
       "parameters" to listOf(mapOf("name" to "param", "in" to QUERY, "description" to "description")),
       "requestBody" to null,
-      "responses" to mapOf("302" to mapOf("description" to "desc")),
+      "responses" to mapOf(Found to mapOf("description" to "desc")),
       "summary" to "summary"
     ))
   }