Security Tools

JWT Signature Verifier (HS256)

Enter a JWT and its secret to verify the signature is valid, computed entirely in your browser.

This only verifies HS256 (symmetric secret) tokens, computed entirely in your browser — nothing is sent anywhere. RS256/ES256 tokens (signed with a private key, verified with a public key) aren't supported here.

How to use this tool

  1. 1Paste the JWT.
  2. 2Enter the secret key.
  3. 3See whether the signature is valid, and the decoded payload.

Frequently asked questions

Does this support RS256 tokens?+

No — this only verifies HS256 (shared-secret) tokens. RS256/ES256 use asymmetric key pairs, a different verification process this tool doesn't implement.

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