What is HMAC used for?

HMAC authenticates messages using a shared secret. It is used in HS256 JWT signing, API webhooks, and request signature verification.

HMAC vs plain SHA-256?

SHA-256 hashes data without a secret. HMAC requires a secret key, preventing attackers from forging valid codes without knowing the key.

Is HMAC the same as password hashing?

No. HMAC is fast by design. Password hashing uses slow algorithms like bcrypt or Argon2.

Tool

HMAC Generator

Compute HMAC-SHA256, HMAC-SHA384, and HMAC-SHA512 message authentication codes.

Last updated April 1, 2026

Runs entirely in your browser — no data sent to servers. Privacy policy

Prove it runs locally

Open DevTools → Network tab
Click Generate
Confirm zero outbound requests for the secret

Generation uses crypto.getRandomValues() in your browser. Privacy policy

Message

Secret key

Algorithm

HMAC (hex)

Enter a message and secret, then click "Generate HMAC".

Treat HMAC secrets like passwords — never paste production secrets into online tools. HMAC is used internally by HS256 JWT signing. All computation runs client-side.

Enter the message to authenticate and your secret key.

Select HMAC algorithm: SHA-256 (most common), SHA-384, or SHA-512.

Click Generate HMAC to compute the authentication code.

Use HMAC for API request signing, webhook verification, and understanding HS256 JWT internals.

const crypto = require('crypto');
const hmac = crypto.createHmac('sha256', secret)
  .update(message)
  .digest('hex');

const crypto = require('crypto');
const hmac = crypto.createHmac('sha256', secret)
  .update(message)
  .digest('hex');

import hmac
import hashlib
digest = hmac.new(secret.encode(), message.encode(), hashlib.sha256).hexdigest()

import (
    "crypto/hmac"
    "crypto/sha256"
    "encoding/hex"
)
mac := hmac.New(sha256.New, []byte(secret))
mac.Write([]byte(message))
hash := hex.EncodeToString(mac.Sum(nil))

Continue learning

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How to Use This Tool

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