HMAC Generator
Sign a message with a secret key, or check a webhook signature.
Private: your files never leave your device.
How it works
- Choose your files.
- Adjust the settings if you like.
- Download the result, or send it to another device with BroAllDone.
Frequently asked questions
How do I create an HMAC?
Type the message and the secret key, and choose the algorithm. The signature appears as you type, ready to copy.
How do I check a webhook signature?
Paste the request body as the message and your webhook secret as the key, then paste the signature from the header into Check a signature. Prefixes like sha256= are understood.
My key is in hex or Base64. Can I use it?
Yes. Choose Key is Hex or Base64 so the key's bytes are used, not its text.
Which output format do I need?
Most APIs use hex. Some use Base64 or Base64URL, and GitHub-style webhooks use sha256= followed by hex.
Which algorithms are supported?
HMAC with SHA-256, SHA-384, SHA-512, SHA-1, MD5, SHA3-256 and SHA3-512.
Is my key safe?
Yes. Everything happens in your browser, so your message and key never leave your device.
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