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JWT Decoder

Inspect JWT headers and payloads, with expiry checks. Decode JSON Web Tokens and inspect header and payload as formatted JSON. Automatic expiry and issued-at checks. Free online JWT debugger.

Cet outil fonctionne à 100 % dans votre navigateur. Vos saisies ne sont jamais envoyées à un serveur : vous pouvez même passer hors ligne après le chargement de la page.

À propos de JWT Decoder

A JWT carries three Base64URL blocks — header, payload and signature — and debugging an API usually starts with "what is actually in this token?". Paste one here to see the algorithm in its header, every claim in its payload as formatted JSON, and human-readable timestamps for issued-at, not-before and expiry, including a live verdict on whether the token has expired. Signatures are not verified (that requires the secret), but the structure and claims are fully decoded.

Comment utiliser JWT Decoder

  1. Paste the full JWT (all three dot-separated parts).
  2. Review the decoded header for the signing algorithm.
  3. Inspect the payload claims and timestamps.
  4. Check the expiry verdict before blaming your API.

Fonctionnalités clés

Does decoding a JWT require the secret key?
No. The header and payload are only Base64URL-encoded, not encrypted, so anyone can read them. Verifying the signature — proving the token was not tampered with — does require the secret or public key.
Is it safe to paste a JWT here?
The decoding happens entirely in your browser and nothing is transmitted. Even so, treat tokens like passwords and avoid sharing them publicly.

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