diff --git a/packages/restate-sdk/src/context_impl.ts b/packages/restate-sdk/src/context_impl.ts
index 982bca9d..cc6654cf 100644
--- a/packages/restate-sdk/src/context_impl.ts
+++ b/packages/restate-sdk/src/context_impl.ts
@@ -44,7 +44,6 @@ import {
 } from "./types/errors.js";
 import type { Client, SendClient } from "./types/rpc.js";
 import {
-  defaultSerde,
   HandlerKind,
   makeRpcCallProxy,
   makeRpcSendProxy,
@@ -96,6 +95,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
   private readonly outputPump: OutputPump;
   private readonly runClosuresTracker: RunClosuresTracker;
   readonly promisesExecutor: PromisesExecutor;
+  readonly defaultSerde: Serde<any>;
 
   constructor(
     readonly coreVm: vm.WasmVM,
@@ -108,6 +108,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
     inputReader: ReadableStreamDefaultReader<Uint8Array>,
     outputWriter: WritableStreamDefaultWriter<Uint8Array>,
     readonly journalValueCodec: JournalValueCodec,
+    defaultSerde?: Serde<any>,
     private readonly asTerminalError?: (error: any) => TerminalError | undefined
   ) {
     this.rand = new RandImpl(input.random_seed, () => {
@@ -131,6 +132,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
       this.runClosuresTracker,
       this.promiseExecutorErrorCallback.bind(this)
     );
+    this.defaultSerde = defaultSerde ?? serde.json;
   }
 
   cancel(invocationId: InvocationId): void {
@@ -146,7 +148,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
       WasmCommandType.AttachInvocation,
       () => {},
       (vm) => vm.sys_attach_invocation(invocationId),
-      SuccessWithSerde(serde ?? defaultSerde(), this.journalValueCodec),
+      SuccessWithSerde(serde ?? this.defaultSerde, this.journalValueCodec),
       Failure
     );
   }
@@ -173,7 +175,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
       () => {},
       (vm) => vm.sys_get_state(name),
       VoidAsNull,
-      SuccessWithSerde(serde ?? defaultSerde(), this.journalValueCodec)
+      SuccessWithSerde(serde ?? this.defaultSerde, this.journalValueCodec)
     );
   }
 
@@ -191,7 +193,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
       WasmCommandType.SetState,
       () =>
         this.journalValueCodec.encode(
-          (serde ?? defaultSerde()).serialize(value)
+          (serde ?? this.defaultSerde).serialize(value)
         ),
       (vm, bytes) => vm.sys_set_state(name, bytes)
     );
@@ -344,21 +346,36 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
   }
 
   serviceClient<D>({ name }: ServiceDefinitionFrom<D>): Client<Service<D>> {
-    return makeRpcCallProxy((call) => this.genericCall(call), name);
+    return makeRpcCallProxy(
+      (call) => this.genericCall(call),
+      this.defaultSerde,
+
+      name
+    );
   }
 
   objectClient<D>(
     { name }: VirtualObjectDefinitionFrom<D>,
     key: string
   ): Client<VirtualObject<D>> {
-    return makeRpcCallProxy((call) => this.genericCall(call), name, key);
+    return makeRpcCallProxy(
+      (call) => this.genericCall(call),
+      this.defaultSerde,
+      name,
+      key
+    );
   }
 
   workflowClient<D>(
     { name }: WorkflowDefinitionFrom<D>,
     key: string
   ): Client<Workflow<D>> {
-    return makeRpcCallProxy((call) => this.genericCall(call), name, key);
+    return makeRpcCallProxy(
+      (call) => this.genericCall(call),
+      this.defaultSerde,
+      name,
+      key
+    );
   }
 
   public serviceSendClient<D>(
@@ -367,6 +384,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
   ): SendClient<Service<D>> {
     return makeRpcSendProxy(
       (send) => this.genericSend(send),
+      this.defaultSerde,
       name,
       undefined,
       opts?.delay
@@ -380,6 +398,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
   ): SendClient<VirtualObject<D>> {
     return makeRpcSendProxy(
       (send) => this.genericSend(send),
+      this.defaultSerde,
       name,
       key,
       opts?.delay
@@ -393,6 +412,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
   ): SendClient<Workflow<D>> {
     return makeRpcSendProxy(
       (send) => this.genericSend(send),
+      this.defaultSerde,
       name,
       key,
       opts?.delay
@@ -412,7 +432,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
       nameOrAction,
       actionSecondParameter
     );
-    const serde = options?.serde ?? defaultSerde();
+    const serde = options?.serde ?? this.defaultSerde ?? this.defaultSerde;
 
     // Prepare the handle
     let handle: number;
@@ -586,7 +606,7 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
         awakeable.handle,
         completeSignalPromiseUsing(
           VoidAsUndefined,
-          SuccessWithSerde(serde, this.journalValueCodec),
+          SuccessWithSerde(serde ?? this.defaultSerde, this.journalValueCodec),
           Failure
         )
       ),
@@ -606,8 +626,8 @@ export class ContextImpl implements ObjectContext, WorkflowContext {
         } else {
           value =
             payload !== undefined
-              ? defaultSerde().serialize(payload)
-              : defaultSerde().serialize(null);
+              ? this.defaultSerde.serialize(payload)
+              : this.defaultSerde.serialize(null);
         }
         return this.journalValueCodec.encode(value);
       },
@@ -793,7 +813,7 @@ class DurablePromiseImpl<T> implements DurablePromise<T> {
     private readonly name: string,
     serde?: Serde<T>
   ) {
-    this.serde = serde ?? defaultSerde();
+    this.serde = serde ?? (this.ctx.defaultSerde as unknown as Serde<T>);
   }
 
   then<TResult1 = T, TResult2 = never>(
@@ -981,7 +1001,7 @@ const VoidAsUndefined: Completer = (value, prom) => {
 };
 
 function SuccessWithSerde<T>(
-  serde?: Serde<T>,
+  serde: Serde<T>,
   journalCodec?: JournalValueCodec,
   transform?: <U>(success: T) => U
 ): Completer {
@@ -995,12 +1015,7 @@ function SuccessWithSerde<T>(
     } else {
       buffer = value.Success;
     }
-    let val: T;
-    if (serde) {
-      val = serde.deserialize(buffer);
-    } else {
-      val = defaultSerde<T>().deserialize(buffer);
-    }
+    let val = serde.deserialize(buffer);
     if (transform) {
       val = transform(val);
     }
diff --git a/packages/restate-sdk/src/endpoint/components.ts b/packages/restate-sdk/src/endpoint/components.ts
index bb236c25..9607e5e3 100644
--- a/packages/restate-sdk/src/endpoint/components.ts
+++ b/packages/restate-sdk/src/endpoint/components.ts
@@ -21,7 +21,8 @@ import type {
   WorkflowOptions,
 } from "../types/rpc.js";
 import { HandlerKind } from "../types/rpc.js";
-import { millisOrDurationToMillis } from "@restatedev/restate-sdk-core";
+import type { Serde } from "@restatedev/restate-sdk-core";
+import { millisOrDurationToMillis, serde } from "@restatedev/restate-sdk-core";
 
 //
 // Interfaces
@@ -44,17 +45,22 @@ export interface ComponentHandler {
 // Service
 //
 
-function handlerInputDiscovery(handler: HandlerWrapper): d.InputPayload {
+function handlerInputDiscovery(
+  handler: HandlerWrapper,
+  defaultSerde: Serde<any>
+): d.InputPayload {
+  const serde = handler.inputSerde ?? defaultSerde;
+
   let contentType = undefined;
   let jsonSchema = undefined;
 
-  if (handler.inputSerde.jsonSchema) {
-    jsonSchema = handler.inputSerde.jsonSchema;
-    contentType = handler.accept ?? handler.inputSerde.contentType;
+  if (serde.jsonSchema) {
+    jsonSchema = serde.jsonSchema;
+    contentType = handler.accept ?? serde.contentType;
   } else if (handler.accept) {
     contentType = handler.accept;
-  } else if (handler.inputSerde.contentType) {
-    contentType = handler.inputSerde.contentType;
+  } else if (serde.contentType) {
+    contentType = serde.contentType;
   } else {
     // no input information
     return {};
@@ -67,20 +73,20 @@ function handlerInputDiscovery(handler: HandlerWrapper): d.InputPayload {
   };
 }
 
-function handlerOutputDiscovery(handler: HandlerWrapper): d.OutputPayload {
+function handlerOutputDiscovery(
+  handler: HandlerWrapper,
+  defaultSerde: Serde<any>
+): d.OutputPayload {
+  const serde = handler.outputSerde ?? defaultSerde;
+
   let contentType = undefined;
   let jsonSchema = undefined;
 
-  if (handler.outputSerde.jsonSchema) {
-    jsonSchema = handler.outputSerde.jsonSchema;
-    contentType =
-      handler.contentType ??
-      handler.outputSerde.contentType ??
-      "application/json";
-  } else if (handler.contentType) {
-    contentType = handler.contentType;
-  } else if (handler.outputSerde.contentType) {
-    contentType = handler.outputSerde.contentType;
+  if (serde.jsonSchema) {
+    jsonSchema = serde.jsonSchema;
+    contentType = serde.contentType ?? "application/json";
+  } else if (serde.contentType) {
+    contentType = serde.contentType;
   } else {
     // no input information
     return { setContentTypeIfEmpty: false };
@@ -116,7 +122,10 @@ export class ServiceComponent implements Component {
       ([name, handler]) => {
         return {
           name,
-          ...commonHandlerOptions(handler.handlerWrapper),
+          ...commonHandlerOptions(
+            handler.handlerWrapper,
+            this.options?.serde ?? serde.json
+          ),
         } satisfies d.Handler;
       }
     );
@@ -188,7 +197,10 @@ export class VirtualObjectComponent implements Component {
         return {
           name,
           ty: handler.kind() === HandlerKind.EXCLUSIVE ? "EXCLUSIVE" : "SHARED",
-          ...commonHandlerOptions(handler.handlerWrapper),
+          ...commonHandlerOptions(
+            handler.handlerWrapper,
+            this.options?.serde ?? serde.json
+          ),
         } satisfies d.Handler;
       }
     );
@@ -263,7 +275,10 @@ export class WorkflowComponent implements Component {
             this.options?.workflowRetention !== undefined
               ? millisOrDurationToMillis(this.options?.workflowRetention)
               : undefined,
-          ...commonHandlerOptions(handler.handlerWrapper),
+          ...commonHandlerOptions(
+            handler.handlerWrapper,
+            this.options?.serde ?? serde.json
+          ),
         } satisfies d.Handler;
       }
     );
@@ -382,10 +397,13 @@ function commonServiceOptions(
   };
 }
 
-function commonHandlerOptions(wrapper: HandlerWrapper) {
+function commonHandlerOptions(
+  wrapper: HandlerWrapper,
+  defaultSerde: Serde<any>
+) {
   return {
-    input: handlerInputDiscovery(wrapper),
-    output: handlerOutputDiscovery(wrapper),
+    input: handlerInputDiscovery(wrapper, defaultSerde),
+    output: handlerOutputDiscovery(wrapper, defaultSerde),
     journalRetention:
       wrapper.journalRetention !== undefined
         ? millisOrDurationToMillis(wrapper.journalRetention)
diff --git a/packages/restate-sdk/src/endpoint/handlers/generic.ts b/packages/restate-sdk/src/endpoint/handlers/generic.ts
index 1a45036c..f776aec0 100644
--- a/packages/restate-sdk/src/endpoint/handlers/generic.ts
+++ b/packages/restate-sdk/src/endpoint/handlers/generic.ts
@@ -386,6 +386,7 @@ export class GenericHandler implements RestateHandler {
         inputReader,
         outputWriter,
         journalValueCodec,
+        service.options?.serde,
         service.options?.asTerminalError
       );
 
diff --git a/packages/restate-sdk/src/types/rpc.ts b/packages/restate-sdk/src/types/rpc.ts
index cb1eb2db..3732f6dc 100644
--- a/packages/restate-sdk/src/types/rpc.ts
+++ b/packages/restate-sdk/src/types/rpc.ts
@@ -36,7 +36,6 @@ import {
   type WorkflowSharedHandler,
   type Serde,
   type Duration,
-  serde,
 } from "@restatedev/restate-sdk-core";
 import { ensureError, TerminalError } from "./errors.js";
 
@@ -168,12 +167,9 @@ function optsFromArgs(args: unknown[]): {
   };
 }
 
-export const defaultSerde = <T>(): Serde<T> => {
-  return serde.json as Serde<T>;
-};
-
 export const makeRpcCallProxy = <T>(
   genericCall: (call: GenericCall<unknown, unknown>) => Promise<unknown>,
+  defaultSerde: Serde<any>,
   service: string,
   key?: string
 ): T => {
@@ -184,10 +180,10 @@ export const makeRpcCallProxy = <T>(
         const method = prop as string;
         return (...args: unknown[]) => {
           const { parameter, opts } = optsFromArgs(args);
-          const requestSerde = opts?.input ?? defaultSerde();
+          const requestSerde = opts?.input ?? defaultSerde;
           const responseSerde =
             (opts as ClientCallOptions<unknown, unknown> | undefined)?.output ??
-            defaultSerde();
+            defaultSerde;
           return genericCall({
             service,
             method,
@@ -208,6 +204,7 @@ export const makeRpcCallProxy = <T>(
 
 export const makeRpcSendProxy = <T>(
   genericSend: (send: GenericSend<unknown>) => void,
+  defaultSerde: Serde<any>,
   service: string,
   key?: string,
   legacyDelay?: number
@@ -219,7 +216,7 @@ export const makeRpcSendProxy = <T>(
         const method = prop as string;
         return (...args: unknown[]) => {
           const { parameter, opts } = optsFromArgs(args);
-          const requestSerde = opts?.input ?? defaultSerde();
+          const requestSerde = opts?.input ?? defaultSerde;
           const delay =
             legacyDelay ??
             (opts as ClientSendOptions<unknown> | undefined)?.delay;
@@ -400,9 +397,6 @@ export class HandlerWrapper {
       | ObjectHandlerOpts<unknown, unknown>
       | WorkflowHandlerOpts<unknown, unknown>
   ): HandlerWrapper {
-    const inputSerde: Serde<unknown> = opts?.input ?? defaultSerde();
-    const outputSerde: Serde<unknown> = opts?.output ?? defaultSerde();
-
     // we must create here a copy of the handler
     // to be able to reuse the original handler in other places.
     // like for example the same logic but under different routes.
@@ -413,8 +407,8 @@ export class HandlerWrapper {
     return new HandlerWrapper(
       kind,
       handlerCopy,
-      inputSerde,
-      outputSerde,
+      opts?.input,
+      opts?.output,
       opts?.accept,
       opts?.description,
       opts?.metadata,
@@ -435,15 +429,12 @@ export class HandlerWrapper {
     return handler[HANDLER_SYMBOL] as HandlerWrapper | undefined;
   }
 
-  public readonly accept?: string;
-  public readonly contentType?: string;
-
   private constructor(
     public readonly kind: HandlerKind,
     private handler: Function,
-    public readonly inputSerde: Serde<unknown>,
-    public readonly outputSerde: Serde<unknown>,
-    accept?: string,
+    public readonly inputSerde?: Serde<unknown>,
+    public readonly outputSerde?: Serde<unknown>,
+    public readonly accept?: string,
     public readonly description?: string,
     public readonly metadata?: Record<string, string>,
     public readonly idempotencyRetention?: Duration | number,
@@ -454,19 +445,16 @@ export class HandlerWrapper {
     public readonly enableLazyState?: boolean,
     public readonly retryPolicy?: RetryPolicy,
     public readonly asTerminalError?: (error: any) => TerminalError | undefined
-  ) {
-    this.accept = accept !== undefined ? accept : inputSerde.contentType;
-    this.contentType = outputSerde.contentType;
-  }
+  ) {}
 
   bindInstance(t: unknown) {
     this.handler = this.handler.bind(t) as Function;
   }
 
-  async invoke(context: unknown, input: Uint8Array) {
+  async invoke(context: { defaultSerde: Serde<any> }, input: Uint8Array) {
     let req: unknown;
     try {
-      req = this.inputSerde.deserialize(input);
+      req = (this.inputSerde ?? context.defaultSerde).deserialize(input);
     } catch (e) {
       const error = ensureError(e);
       throw new TerminalError(`Failed to deserialize input: ${error.message}`, {
@@ -474,7 +462,7 @@ export class HandlerWrapper {
       });
     }
     const res: unknown = await this.handler(context, req);
-    return this.outputSerde.serialize(res);
+    return (this.outputSerde ?? context.defaultSerde).serialize(res);
   }
 
   /**
@@ -887,6 +875,13 @@ export type ServiceOptions = {
    * ```
    */
   asTerminalError?: (error: any) => TerminalError | undefined;
+
+  /**
+   * Default serde to use for requests, responses, state, side effects, awakeables, promises. Used when no other serde is specified.
+   *
+   * If not provided, defaults to `serde.json`.
+   */
+  serde?: Serde<any>;
 };
 
 /**