HMAC Generator & Verifier

Computes an HMAC (SHA-256, SHA-384, or SHA-512) of a text message or local file using exclusively the browser's crypto.subtle — never a manual implementation or a plain hash presented as HMAC. Accepts the secret in text, hexadecimal, Base64, or Base64URL, shows the result in hex/Base64/Base64URL, and verifies an existing signature with a resistant comparison. The secret is never shown by default, never included in downloaded reports, and never logged.

Processed on your device, no AIhasta 5.000.000 de caracteres o 100 MB de archivo

The message, secret, and result stay on your device.

Text message

or use a local file

Secret

Encoding

Algorithm

Output encoding

The data is processed on your device and is never sent to the server.

Use cases

Compute the HMAC signature of a webhook to test it
Verify that a received HMAC matches the expected one
Generate an HMAC of a local file

How to use this tool

Enter the message or upload a file
Enter the secret and choose the algorithm
Generate or verify the HMAC

Frequently asked questions

Is a plain hash the same as an HMAC?

No. A plain hash (like SHA-256 of a message) doesn't use any secret and anyone can recompute it; an HMAC combines the message with a shared secret using a specific cryptographic construction, computed here with crypto.subtle.

Is the secret saved or sent anywhere?

No. The secret stays on your device, is never sent to a server, isn't included in downloaded reports, and isn't logged in analytics.

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