diff --git a/src/index.ts b/src/index.ts
index eabd418..fd1bb3b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -57,19 +57,22 @@ export class GelatoRelay {
 
   /**
    * @param {CallWithSyncFeeRequest} request - CallWithSyncFee request to be relayed by Gelato Executors
+   * @param {string} [sponsorApiKey] Optional Sponsor API key to be used for the call
    * @param {RelayRequestOptions} [options] - Optional Relay configuration
    * @returns {Promise<RelayResponse>} Response object with taskId parameter
    *
    */
   callWithSyncFee = (
     request: CallWithSyncFeeRequest,
+    sponsorApiKey?: string,
     options?: RelayRequestOptions
   ): Promise<RelayResponse> =>
-    library.relayWithSyncFee({ request, options }, this.#config);
+    library.relayWithSyncFee({ request, sponsorApiKey, options }, this.#config);
 
   /**
    * @param {CallWithSyncFeeERC2771Request} request - CallWithSyncFeeERC2771 request to be relayed by Gelato Executors
    * @param {ethers.providers.Web3Provider | ethers.Wallet} walletOrProvider - Web3Provider [front-end] or Wallet [back-end] to sign the payload
+   * @param {string} [sponsorApiKey] Optional Sponsor API key to be used for the call
    * @param {RelayRequestOptions} [options] - Optional Relay configuration
    * @returns {Promise<RelayResponse>} Response object with taskId parameter
    *
@@ -77,12 +80,14 @@ export class GelatoRelay {
   callWithSyncFeeERC2771 = (
     request: CallWithSyncFeeERC2771Request,
     walletOrProvider: ethers.providers.Web3Provider | ethers.Wallet,
+    sponsorApiKey?: string,
     options?: RelayRequestOptions
   ): Promise<RelayResponse> =>
     library.relayWithCallWithSyncFeeERC2771(
       {
         request,
         walletOrProvider,
+        sponsorApiKey,
         options,
       },
       this.#config
diff --git a/src/lib/callWithSyncFee/index.ts b/src/lib/callWithSyncFee/index.ts
index b614ab0..6922504 100644
--- a/src/lib/callWithSyncFee/index.ts
+++ b/src/lib/callWithSyncFee/index.ts
@@ -1,7 +1,9 @@
 import { getHttpErrorMessage, post } from "../../utils";
 import { isNetworkSupported } from "../network";
 import {
+  ApiKey,
   Config,
+  Optional,
   RelayCall,
   RelayRequestOptions,
   RelayResponse,
@@ -12,12 +14,13 @@ import { CallWithSyncFeeRequest } from "./types";
 export const relayWithSyncFee = async (
   payload: {
     request: CallWithSyncFeeRequest;
+    sponsorApiKey?: string;
     options?: RelayRequestOptions;
   },
   config: Config
 ): Promise<RelayResponse> => {
   try {
-    const { request, options } = payload;
+    const { request, options, sponsorApiKey } = payload;
     const isSupported = await isNetworkSupported(
       { chainId: Number(request.chainId) },
       config
@@ -26,7 +29,9 @@ export const relayWithSyncFee = async (
       throw new Error(`Chain id [${request.chainId}] is not supported`);
     }
     return await post<
-      CallWithSyncFeeRequest & RelayRequestOptions,
+      CallWithSyncFeeRequest &
+        RelayRequestOptions &
+        Optional<ApiKey, "sponsorApiKey">,
       RelayResponse
     >(
       {
@@ -35,6 +40,7 @@ export const relayWithSyncFee = async (
           ...request,
           isRelayContext: request.isRelayContext ?? true,
           ...options,
+          sponsorApiKey,
         },
       },
       config
diff --git a/src/lib/erc2771/callWithSyncFeeERC2771/index.ts b/src/lib/erc2771/callWithSyncFeeERC2771/index.ts
index 271552a..86be489 100644
--- a/src/lib/erc2771/callWithSyncFeeERC2771/index.ts
+++ b/src/lib/erc2771/callWithSyncFeeERC2771/index.ts
@@ -8,8 +8,10 @@ import {
 } from "../../../utils";
 import { isNetworkSupported } from "../../network";
 import {
+  ApiKey,
   BaseCallWithSyncFeeParams,
   Config,
+  Optional,
   RelayCall,
   RelayRequestOptions,
   RelayResponse,
@@ -28,12 +30,13 @@ export const relayWithCallWithSyncFeeERC2771 = async (
   payload: {
     request: CallWithSyncFeeERC2771Request;
     walletOrProvider: ethers.providers.Web3Provider | ethers.Wallet;
+    sponsorApiKey?: string;
     options?: RelayRequestOptions;
   },
   config: Config
 ): Promise<RelayResponse> => {
   try {
-    const { request, walletOrProvider, options } = payload;
+    const { request, walletOrProvider, options, sponsorApiKey } = payload;
     if (!walletOrProvider.provider) {
       throw new Error(`Missing provider`);
     }
@@ -70,7 +73,8 @@ export const relayWithCallWithSyncFeeERC2771 = async (
       CallWithERC2771Struct &
         BaseCallWithSyncFeeParams &
         RelayRequestOptions &
-        UserAuthSignature,
+        UserAuthSignature &
+        Optional<ApiKey, "sponsorApiKey">,
       RelayResponse
     >(
       {
@@ -81,6 +85,7 @@ export const relayWithCallWithSyncFeeERC2771 = async (
           feeToken,
           isRelayContext: isRelayContext ?? true,
           userSignature: signature,
+          sponsorApiKey,
         },
       },
       config