diff --git a/packages/auth-server-api/.env.example b/packages/auth-server-api/.env.example
index 95527073..c2289bc7 100644
--- a/packages/auth-server-api/.env.example
+++ b/packages/auth-server-api/.env.example
@@ -9,7 +9,6 @@ CORS_ORIGINS=http://localhost:3003,http://localhost:3002,http://localhost:3000
 DEPLOYER_PRIVATE_KEY=0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80
 
 # Blockchain Configuration
-CHAIN_ID=1337
 RPC_URL=http://127.0.0.1:8545
 BUNDLER_URL=http://127.0.0.1:4337
 
diff --git a/packages/auth-server-api/src/config.ts b/packages/auth-server-api/src/config.ts
index 9d0084fe..e059c041 100644
--- a/packages/auth-server-api/src/config.ts
+++ b/packages/auth-server-api/src/config.ts
@@ -2,6 +2,8 @@ import dotenv from "dotenv";
 import { readFileSync } from "fs";
 import { dirname, join } from "path";
 import { fileURLToPath } from "url";
+import type { Chain } from "viem";
+import { localhost, sepolia } from "viem/chains";
 import { z } from "zod";
 
 // Load environment variables
@@ -31,7 +33,6 @@ const envSchema = z.object({
   PORT: z.string().default("3004"),
   CORS_ORIGINS: z.string().default("http://localhost:3003,http://localhost:3002,http://localhost:3000"),
   DEPLOYER_PRIVATE_KEY: z.string().default("0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80"),
-  CHAIN_ID: z.string().default("1337"),
   RPC_URL: z.string().default("http://127.0.0.1:8545"),
   BUNDLER_URL: z.string().default("http://127.0.0.1:4337"),
   FACTORY_ADDRESS: z.string().optional(),
@@ -67,4 +68,15 @@ if (!FACTORY_ADDRESS || !EOA_VALIDATOR_ADDRESS || !WEBAUTHN_VALIDATOR_ADDRESS ||
   process.exit(1);
 }
 
-export { env, EOA_VALIDATOR_ADDRESS, FACTORY_ADDRESS, SESSION_VALIDATOR_ADDRESS, WEBAUTHN_VALIDATOR_ADDRESS };
+// Supported chains configuration
+const SUPPORTED_CHAINS: Chain[] = [localhost, sepolia];
+
+function getChain(chainId: number): Chain {
+  const chain = SUPPORTED_CHAINS.find((c) => c.id === chainId);
+  if (!chain) {
+    throw new Error(`Unsupported chainId: ${chainId}. Supported: ${SUPPORTED_CHAINS.map((c) => c.id).join(", ")}`);
+  }
+  return chain;
+}
+
+export { env, EOA_VALIDATOR_ADDRESS, FACTORY_ADDRESS, getChain, SESSION_VALIDATOR_ADDRESS, SUPPORTED_CHAINS, WEBAUTHN_VALIDATOR_ADDRESS };
diff --git a/packages/auth-server-api/src/handlers/deploy-account.ts b/packages/auth-server-api/src/handlers/deploy-account.ts
index f6194fb3..c1d74b4b 100644
--- a/packages/auth-server-api/src/handlers/deploy-account.ts
+++ b/packages/auth-server-api/src/handlers/deploy-account.ts
@@ -2,11 +2,9 @@ import type { Request, Response } from "express";
 import { type Address, createPublicClient, createWalletClient, type Hex, http } from "viem";
 import { privateKeyToAccount } from "viem/accounts";
 import { waitForTransactionReceipt } from "viem/actions";
-import { localhost } from "viem/chains";
-import { getAccountAddressFromLogs, prepareDeploySmartAccount, type SessionSpecJSON } from "zksync-sso-4337/client";
-import { parseSessionConfigJSON } from "zksync-sso-4337/client-auth-server";
+import { getAccountAddressFromLogs, prepareDeploySmartAccount } from "zksync-sso-4337/client";
 
-import { env, EOA_VALIDATOR_ADDRESS, FACTORY_ADDRESS, SESSION_VALIDATOR_ADDRESS, WEBAUTHN_VALIDATOR_ADDRESS } from "../config.js";
+import { env, EOA_VALIDATOR_ADDRESS, FACTORY_ADDRESS, getChain, SESSION_VALIDATOR_ADDRESS, WEBAUTHN_VALIDATOR_ADDRESS } from "../config.js";
 import { deployAccountSchema } from "../schemas.js";
 
 type DeployAccountRequest = {
@@ -14,7 +12,6 @@ type DeployAccountRequest = {
   credentialId: Hex;
   credentialPublicKey: { x: Hex; y: Hex };
   originDomain: string;
-  session?: SessionSpecJSON;
   userId?: string;
   eoaSigners?: Address[];
 };
@@ -33,21 +30,19 @@ export const deployAccountHandler = async (req: Request, res: Response): Promise
 
     const body = req.body as DeployAccountRequest;
 
-    // Convert session from JSON (with string bigints) to SessionSpec (with actual bigints)
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    const initialSession = body.session ? parseSessionConfigJSON(body.session) : undefined;
-    // TODO: Use initialSession during deployment
+    // Get chain from request
+    const chain = getChain(body.chainId);
 
     // Create clients
     const publicClient = createPublicClient({
-      chain: localhost,
+      chain,
       transport: http(env.RPC_URL),
     });
 
     const deployerAccount = privateKeyToAccount(env.DEPLOYER_PRIVATE_KEY as Hex);
     const walletClient = createWalletClient({
       account: deployerAccount,
-      chain: localhost,
+      chain,
       transport: http(env.RPC_URL),
     });