What does HMAC Generator actually do?

The HMAC generator computes a keyed hash of a message. You need the same key, algorithm, and exact bytes as the API, including whether the message is the raw body or a canonical string. HMAC is not a JWT, and it is not encryption. The key and message are processed locally.

Are my HMAC secrets uploaded?

No. Signing runs locally in your browser.

Which algorithms are supported?

Common options include SHA-256 and SHA-512 — check the tool UI for the full list.

Yes — free online HMAC generation with no account.

HMAC Generator

Generate HMAC-SHA1/256/384/512 signatures for API request signing. UTF-8/hex/base64 input. Free online — runs locally, no upload.

Algorithm

Output format

Secret key

Message

HMAC-SHA256 (hex)

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HMAC signs a message with a secret key, producing a fixed-length signature. Used for API request signing (e.g. AWS SigV4, Stripe webhooks), cookie integrity, and JWT signing. Computed locally using the browser's native Web Crypto API.

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HMAC Generator