JWT Decoder

Decode JWT headers + payloads. Surfaces issued, expires, and notBefore timestamps.

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Encoded token
Decoded entirely in your browser — the token never leaves your device.

Decode a JSON Web Token to inspect its header, payload, and claims — and verify its HMAC signature with your secret, right in the browser. Edit the header or payload and the token re-signs live.

How to use JWT Decoder

  1. 1Paste a JWT (header.payload.signature) into the input.
  2. 2Read the decoded header and payload, plus a plain-English claims table.
  3. 3Enter the shared secret to verify an HS256/384/512 signature.
  4. 4Edit the header or payload to re-issue a new signed token.

Frequently asked questions

Yes, for HMAC algorithms (HS256, HS384, HS512) — enter the shared secret and you’ll see a Valid or Invalid badge instantly. Asymmetric algorithms (RS/ES/PS) need the issuer’s public key, which isn’t entered here.
Decoding and verification happen entirely in your browser — the token and secret are never sent anywhere. That said, treat production tokens with care and avoid sharing your screen.
They’re timestamps: iat is when the token was issued, nbf is the earliest it’s valid, and exp is when it expires. The tool shows each as a readable date plus a relative time like “expires in 2 days”.
Yes. Edit the header or payload fields and, with a secret entered, the token is re-signed live so you can craft test tokens.
Yes, completely free with no sign-up, no watermark, and no daily limits. Use it as much as you like.

Still have questions?

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