diff --git a/packages/api/package.json b/packages/api/package.json
index 955b3ad..a6d71e3 100644
--- a/packages/api/package.json
+++ b/packages/api/package.json
@@ -34,12 +34,8 @@
     "clean": true,
     "platform": "browser"
   },
-  "dependencies": {
-    "crypto-js": "^4.2.0"
-  },
-  "devDependencies": {
-    "@types/crypto-js": "^4.2.0"
-  },
+  "dependencies": {},
+  "devDependencies": {},
   "peerDependencies": {},
   "keywords": [
     "ton",
diff --git a/packages/api/src/utils/verify-signature.ts b/packages/api/src/utils/verify-signature.ts
index 2ddac0b..a99518b 100644
--- a/packages/api/src/utils/verify-signature.ts
+++ b/packages/api/src/utils/verify-signature.ts
@@ -1,5 +1,3 @@
-import * as CryptoJS from 'crypto-js';
-
 /**
  * Verifies the HMAC-SHA256 signature of a payload
  * @param payload - Raw JSON string or object to verify
@@ -12,11 +10,11 @@ import * as CryptoJS from 'crypto-js';
  * import { verifySignature } from "@ton-pay/api";
  *
  * // With raw string
- * app.post("/webhook", (req, res) => {
+ * app.post("/webhook", async (req, res) => {
  *   const signature = req.headers["x-tonpay-signature"] as string;
  *   const payload = JSON.stringify(req.body);
  *
- *   if (!verifySignature(payload, signature, YOUR_API_SECRET)) {
+ *   if (!await verifySignature(payload, signature, YOUR_API_SECRET)) {
  *     return res.status(401).json({ error: "Invalid signature" });
  *   }
  *
@@ -24,10 +22,10 @@ import * as CryptoJS from 'crypto-js';
  * });
  *
  * // With object (will be stringified automatically)
- * app.post("/webhook", (req, res) => {
+ * app.post("/webhook", async (req, res) => {
  *   const signature = req.headers["x-tonpay-signature"] as string;
  *
- *   if (!verifySignature(req.body, signature, YOUR_API_SECRET)) {
+ *   if (!await verifySignature(req.body, signature, YOUR_API_SECRET)) {
  *     return res.status(401).json({ error: "Invalid signature" });
  *   }
  *
@@ -35,16 +33,31 @@ import * as CryptoJS from 'crypto-js';
  * });
  * ```
  */
-export function verifySignature(
+export async function verifySignature(
   payload: string | object,
   signature: string,
   apiSecret: string,
-): boolean {
+): Promise<boolean> {
+  const encoder = new TextEncoder();
   const payloadString =
     typeof payload === 'string' ? payload : JSON.stringify(payload);
 
-  const hmac = CryptoJS.HmacSHA256(payloadString, apiSecret);
-  const expectedSignature = `sha256=${hmac.toString(CryptoJS.enc.Hex)}`;
+  const key = await crypto.subtle.importKey(
+    'raw',
+    encoder.encode(apiSecret),
+    { name: 'HMAC', hash: 'SHA-256' },
+    false,
+    ['sign'],
+  );
+
+  const sig = await crypto.subtle.sign(
+    'HMAC',
+    key,
+    encoder.encode(payloadString),
+  );
+  const hex = Array.from(new Uint8Array(sig))
+    .map((b) => b.toString(16).padStart(2, '0'))
+    .join('');
 
-  return signature === expectedSignature;
+  return signature === `sha256=${hex}`;
 }
diff --git a/packages/api/tsup.config.ts b/packages/api/tsup.config.ts
index 0e5845c..0ba9296 100644
--- a/packages/api/tsup.config.ts
+++ b/packages/api/tsup.config.ts
@@ -8,6 +8,5 @@ export default defineConfig({
   sourcemap: true,
   clean: true,
   platform: 'browser',
-  noExternal: ['crypto-js'],
   tsconfig: './tsconfig.json',
 });