diff --git a/README.md b/README.md
index 90704a3..dd368fd 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ console.log(r3);
 ## Server
 
 ```ts
-import { respond } from "../server/mod.ts";
+import { numberArrayValidator, respond } from "../server/mod.ts";
 
 function add([a, b]: [number, number]) {
   return a + b;
@@ -52,7 +52,7 @@ function animalsMakeNoise(noise: string[]) {
 }
 
 const methods = {
-  add: add,
+  add: { method: add, validation: numberArrayValidator },
   makeName: makeName,
   animalsMakeNoise: animalsMakeNoise,
 };
diff --git a/client/client.ts b/client/client.ts
index fae6a72..02ddb66 100644
--- a/client/client.ts
+++ b/client/client.ts
@@ -1,4 +1,4 @@
-import { JsonValue, RpcBatchRequest, RpcRequest } from "../rpc_types.ts";
+import { JsonValue, RpcBatchRequest, RpcRequest } from "../types.ts";
 import {
   createRequest as createRpcRequest,
   type CreateRequestInput,
diff --git a/client/creation.ts b/client/creation.ts
index 28d5204..86995ec 100644
--- a/client/creation.ts
+++ b/client/creation.ts
@@ -1,4 +1,4 @@
-import { RpcRequest } from "../rpc_types.ts";
+import { RpcRequest } from "../types.ts";
 import { generateUlid } from "./deps.ts";
 
 export type CreateRequestInput = {
diff --git a/client/validation.ts b/client/validation.ts
index 715f66a..b51a86a 100644
--- a/client/validation.ts
+++ b/client/validation.ts
@@ -3,7 +3,7 @@ import type {
   RpcResponse,
   RpcResponseBasis,
   RpcSuccess,
-} from "../rpc_types.ts";
+} from "../types.ts";
 
 // deno-lint-ignore no-explicit-any
 function validateRpcBasis(data: any): data is RpcResponseBasis {
diff --git a/examples/client.ts b/examples/client.ts
index 0d05faf..ce7d97f 100644
--- a/examples/client.ts
+++ b/examples/client.ts
@@ -7,13 +7,18 @@ const r2 = await call({
   method: "makeName",
   params: { firstName: "Joe", lastName: "Doe" },
 });
+const r3 = await call({
+  method: "add",
+  params: [1, 10],
+});
 
 console.log(r1);
 console.log(r2);
+console.log(r3);
 
 const batchCall = makeBatchRpcCall("http://localhost:8000");
 
-const r3 = await batchCall([{
+const r4 = await batchCall([{
   method: "animalsMakeNoise",
   params: ["aaa", "bbb"],
 }, {
@@ -21,4 +26,4 @@ const r3 = await batchCall([{
   params: ["aaa", "bbb"],
 }, { method: "animalsMakeNoise", params: ["aaa", "bbb"] }]);
 
-console.log(r3);
+console.log(r4);
diff --git a/examples/server.ts b/examples/server.ts
index d107fa3..532a231 100644
--- a/examples/server.ts
+++ b/examples/server.ts
@@ -1,4 +1,4 @@
-import { respond } from "../server/mod.ts";
+import { numberArrayValidator, respond } from "../server/mod.ts";
 
 function add([a, b]: [number, number]) {
   return a + b;
@@ -16,7 +16,7 @@ function animalsMakeNoise(noise: string[]) {
 }
 
 const methods = {
-  add: add,
+  add: { method: add, validation: numberArrayValidator },
   makeName: makeName,
   animalsMakeNoise: animalsMakeNoise,
 };
diff --git a/server/auth.ts b/server/auth.ts
index 11665e4..22faa0d 100644
--- a/server/auth.ts
+++ b/server/auth.ts
@@ -1,18 +1,13 @@
 import { authErrorData } from "./error_data.ts";
-import {
-  getJwtFromBearer,
-  isArray,
-  isFunction,
-  isPresent,
-  type Payload,
-} from "./deps.ts";
+import { getJwtFromBearer, isArray, isFunction, isPresent } from "./deps.ts";
+import { type JsonObject } from "../types.ts";
 import { type CreationInput } from "./creation.ts";
 import { type AuthInput } from "./response.ts";
 import { type ValidationSuccess } from "./validation.ts";
 
 export type AuthData = AuthInput & { headers: Headers };
 type VerifyJwtForSelectedMethodsReturnType = CreationInput & {
-  payload?: Payload;
+  payload?: JsonObject;
 };
 
 export async function verifyJwtForSelectedMethods(
@@ -31,9 +26,9 @@ export async function verifyJwtForSelectedMethods(
       item.validationObject && item.validationObject.isError
     );
     if (errorOrUndefined) {
-      return errorOrUndefined as CreationInput & { payload?: Payload };
+      return errorOrUndefined as CreationInput & { payload?: JsonObject };
     } else if (authResults.length > 0) {
-      return authResults[0] as CreationInput & { payload?: Payload };
+      return authResults[0] as CreationInput & { payload?: JsonObject };
     }
   }
   return { validationObject, methods, options };
diff --git a/server/creation.ts b/server/creation.ts
index f3047d7..ea043b9 100644
--- a/server/creation.ts
+++ b/server/creation.ts
@@ -1,10 +1,15 @@
-import { internalErrorData } from "./error_data.ts";
+import { internalErrorData, validationErrorData } from "./error_data.ts";
 import { CustomError } from "./custom_error.ts";
 import { type AuthData, verifyJwtForSelectedMethods } from "./auth.ts";
-import { type RpcBatchResponse, type RpcResponse } from "../rpc_types.ts";
+import {
+  type JsonObject,
+  type RpcBatchResponse,
+  type RpcResponse,
+} from "../types.ts";
 import { type ValidationObject } from "./validation.ts";
-import { type Methods, type Options } from "./response.ts";
-import { isArray, type Payload } from "./deps.ts";
+import { type Options } from "./response.ts";
+import { type Methods } from "./method.ts";
+import { isArray } from "./deps.ts";
 
 export type CreationInput = {
   validationObject: ValidationObject;
@@ -20,18 +25,36 @@ type RpcBatchResponseOrNull = RpcBatchResponse | null;
 
 async function executeMethods(
   { validationObject, methods, options, payload }: CreationInput & {
-    payload?: Payload;
+    payload?: JsonObject;
   },
 ): Promise<ValidationObject> {
   if (validationObject.isError) return validationObject;
   try {
-    const additionalArgument = { ...options.args, payload };
-    const method = methods[validationObject.method];
+    const params = validationObject.params;
+    const additionalArgument = payload
+      ? { ...options.args, payload }
+      : { ...options.args };
+    const methodOrObject = methods[validationObject.method];
+    const { method, validation } = typeof methodOrObject === "function"
+      ? { method: methodOrObject, validation: null }
+      : methodOrObject;
+    if (validation) {
+      try {
+        validation.parse(params);
+      } catch (error) {
+        return {
+          id: validationObject.id,
+          data: error.data,
+          isError: true,
+          ...validationErrorData,
+        };
+      }
+    }
     return {
       ...validationObject,
       result: Object.keys(additionalArgument).length === 0
-        ? await method(validationObject.params)
-        : await method(validationObject.params, additionalArgument),
+        ? await method(params)
+        : await method(params, additionalArgument),
     };
   } catch (error) {
     if (error instanceof CustomError) {
@@ -54,7 +77,7 @@ async function executeMethods(
 
 async function createRpcResponse(
   { validationObject, methods, options, payload }: CreationInput & {
-    payload?: Payload;
+    payload?: JsonObject;
   },
 ): Promise<RpcResponseOrNull> {
   const obj: ValidationObject = await executeMethods(
diff --git a/server/custom_error.ts b/server/custom_error.ts
index 79e8d62..d4a9d05 100644
--- a/server/custom_error.ts
+++ b/server/custom_error.ts
@@ -1,4 +1,4 @@
-import { type JsonValue } from "../rpc_types.ts";
+import { type JsonValue } from "../types.ts";
 
 export class CustomError extends Error {
   code: number;
diff --git a/server/deps.ts b/server/deps.ts
index a70c76f..7013d61 100644
--- a/server/deps.ts
+++ b/server/deps.ts
@@ -1,8 +1,4 @@
-export {
-  type Payload,
-  type VerifyOptions,
-} from "https://dev.zaubrik.com/djwt@v3.0.2/mod.ts";
-
+export { type VerifyOptions } from "https://dev.zaubrik.com/djwt@v3.0.2/mod.ts";
 export {
   type CryptoKeyOrUpdateInput,
   getJwtFromBearer,
@@ -16,3 +12,4 @@ export {
   isPresent,
   isString,
 } from "https://dev.zaubrik.com/sorcery@v0.1.5/type.js";
+export { type Type } from "https://deno.land/x/valita@v0.3.8/mod.ts";
diff --git a/server/error_data.ts b/server/error_data.ts
index 73952c8..b451c79 100644
--- a/server/error_data.ts
+++ b/server/error_data.ts
@@ -17,3 +17,7 @@ export const invalidRequestErrorData = {
  * -32000 to -32099 Reserved for implementation-defined server-errors.
  */
 export const authErrorData = { code: -32020, message: "Authorization error" };
+export const validationErrorData = {
+  code: -32030,
+  message: "Validation error",
+};
diff --git a/server/method.ts b/server/method.ts
new file mode 100644
index 0000000..59b0bdd
--- /dev/null
+++ b/server/method.ts
@@ -0,0 +1,12 @@
+import { type JsonValue } from "../types.ts";
+import { type Type } from "./deps.ts";
+
+// deno-lint-ignore no-explicit-any
+export type Method = (...args: any[]) => JsonValue | Promise<JsonValue>;
+export type Methods = {
+  [method: string]: Method | {
+    method: Method;
+    // deno-lint-ignore no-explicit-any
+    validation: Type<any>;
+  };
+};
diff --git a/server/mod.ts b/server/mod.ts
index 488505a..ab9a8c4 100644
--- a/server/mod.ts
+++ b/server/mod.ts
@@ -1 +1,3 @@
 export * from "./response.ts";
+export * from "./method.ts";
+export * from "./util.ts";
diff --git a/server/response.ts b/server/response.ts
index f7bfa3b..e23bfc8 100644
--- a/server/response.ts
+++ b/server/response.ts
@@ -6,12 +6,8 @@ import {
 } from "./deps.ts";
 import { createRpcResponseOrBatch } from "./creation.ts";
 import { validateRequest } from "./validation.ts";
-import { type JsonValue } from "../rpc_types.ts";
+import { type Methods } from "./method.ts";
 
-export type Methods = {
-  // deno-lint-ignore no-explicit-any
-  [method: string]: (...arg: any[]) => JsonValue | Promise<JsonValue>;
-};
 export type Options = {
   // Add response headers:
   headers?: Headers;
diff --git a/server/response_test.ts b/server/response_test.ts
index 910df72..e0a82c1 100644
--- a/server/response_test.ts
+++ b/server/response_test.ts
@@ -1,6 +1,8 @@
-import { assertEquals, create, Payload } from "../test_deps.ts";
+import { assertEquals, create } from "../test_deps.ts";
+import { type JsonObject } from "../types.ts";
 import { respond } from "./response.ts";
 import { CustomError } from "./custom_error.ts";
+import { numberArrayValidator } from "../server/util.ts";
 
 function createReq(str: string) {
   return new Request("http://0.0.0.0:8000", { body: str, method: "POST" });
@@ -10,6 +12,10 @@ function removeWhiteSpace(str: string) {
   return JSON.stringify(JSON.parse(str));
 }
 
+function add([a, b]: [number, number]) {
+  return a + b;
+}
+
 const methods = {
   // deno-lint-ignore no-explicit-any
   subtract: (input: any) =>
@@ -28,9 +34,10 @@ const methods = {
       "details": "error details",
     });
   },
-  login: (_: unknown, { payload }: { payload: Payload }) => {
+  login: (_: unknown, { payload }: { payload: JsonObject }) => {
     return payload.user as string;
   },
+  add: { method: add, validation: numberArrayValidator },
 };
 
 const cryptoKey = await crypto.subtle.generateKey(
@@ -238,6 +245,32 @@ Deno.test("rpc call with publicErrorStack set to true", async function (): Promi
   );
 });
 
+Deno.test("rpc call with validation", async function (): Promise<
+  void
+> {
+  const sentToServer =
+    '{"jsonrpc": "2.0", "method": "add", "params": [10, 20], "id": 1}';
+  const sentToClient = '{"jsonrpc":"2.0","result":30,"id":1}';
+
+  assertEquals(
+    await (await respond(methods)(createReq(sentToServer))).text(),
+    removeWhiteSpace(sentToClient),
+  );
+});
+Deno.test("rpc call with failed validation", async function (): Promise<
+  void
+> {
+  const sentToServer =
+    '{"jsonrpc": "2.0", "method": "add", "params": [10, "invalid"], "id": 1}';
+  const sentToClient =
+    '{"jsonrpc":"2.0","error":{"code":-32030,"message":"Validation error"},"id":1}';
+
+  assertEquals(
+    await (await respond(methods)(createReq(sentToServer))).text(),
+    removeWhiteSpace(sentToClient),
+  );
+});
+
 Deno.test("rpc call with a custom error", async function (): Promise<
   void
 > {
diff --git a/server/util.ts b/server/util.ts
new file mode 100644
index 0000000..45203ea
--- /dev/null
+++ b/server/util.ts
@@ -0,0 +1,53 @@
+import { v } from "./util_deps.ts";
+import { type JsonArray, type JsonObject, type JsonValue } from "../types.ts";
+
+export type StringOrNull = string | null;
+export type NumberOrNull = number | null;
+
+// Validators for JsonPrimitive
+export const stringValidator = v.string();
+export const numberValidator = v.number();
+export const booleanValidator = v.boolean();
+export const nullValidator = v.null();
+
+// Validator for JsonPrimitive (union of all primitive types)
+export const primitiveValidator = v.union(
+  stringValidator,
+  numberValidator,
+  booleanValidator,
+  nullValidator,
+);
+
+// Recursive validators for JsonValue, JsonObject, and JsonArray
+export const valueValidator: v.Type<JsonValue> = v.lazy(() =>
+  v.union(primitiveValidator, objectValidator, arrayValidator)
+);
+export const objectValidator: v.Type<JsonObject> = v.lazy(() =>
+  v.record(valueValidator)
+);
+export const arrayValidator: v.Type<JsonArray> = v.lazy(() =>
+  v.array(valueValidator)
+);
+export const stringOrNullValidator: v.Type<StringOrNull> = v.union(
+  stringValidator,
+  nullValidator,
+);
+export const numberOrNullValidator: v.Type<NumberOrNull> = v.union(
+  numberValidator,
+  nullValidator,
+);
+
+// Combination Validators for Arrays and Objects with specific types
+export const stringArrayValidator = v.array(stringValidator);
+export const numberArrayValidator = v.array(numberValidator);
+export const booleanArrayValidator = v.array(booleanValidator);
+export const objectArrayValidator = v.array(objectValidator);
+export const stringOrNullArrayValidator = v.array(stringOrNullValidator);
+export const numberOrNullArrayValidator = v.array(numberOrNullValidator);
+
+export const stringObjectValidator = v.record(stringValidator);
+export const numberObjectValidator = v.record(numberValidator);
+export const booleanObjectValidator = v.record(booleanValidator);
+export const objectObjectValidator = v.record(objectValidator);
+export const stringOrNullObjectValidator = v.record(stringOrNullValidator);
+export const numberOrNullObjectValidator = v.record(numberOrNullValidator);
diff --git a/server/util_deps.ts b/server/util_deps.ts
new file mode 100644
index 0000000..875cd89
--- /dev/null
+++ b/server/util_deps.ts
@@ -0,0 +1 @@
+export * as v from "https://deno.land/x/valita@v0.3.8/mod.ts";
diff --git a/server/validation.ts b/server/validation.ts
index 54799fc..6dcc986 100644
--- a/server/validation.ts
+++ b/server/validation.ts
@@ -5,15 +5,14 @@ import {
   methodNotFoundErrorData,
   parseErrorData,
 } from "./error_data.ts";
-import { type Methods } from "./response.ts";
-
+import { type Methods } from "./method.ts";
 import {
   type JsonArray,
   type JsonObject,
   type JsonValue,
   type RpcId,
   type RpcMethod,
-} from "../rpc_types.ts";
+} from "../types.ts";
 
 export type ValidationSuccess = {
   isError: false;
@@ -98,7 +97,11 @@ export function validateRpcRequestObject(
         id: isRpcId(decodedBody.id) ? decodedBody.id : null,
         isError: true,
       };
-    } else if (!(isFunction(methods[decodedBody.method]))) {
+    } else if (
+      !(isFunction(methods[decodedBody.method]) ||
+        // deno-lint-ignore no-explicit-any
+        isFunction((methods[decodedBody.method] as any)?.method))
+    ) {
       return {
         id: decodedBody.id,
         isError: true,
diff --git a/rpc_types.ts b/types.ts
similarity index 100%
rename from rpc_types.ts
rename to types.ts