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SmaftyTools

JWT Decoder

Decode JWT tokens online — view the header, payload and expiry instantly. Fully client-side, your token never leaves the browser.

Decoding only — the signature is not verified. Never paste production secrets on shared machines.

Header

Decoded header appears here

Payload

Decoded payload appears here

About JWT Decoder

The JWT Decoder splits a JSON Web Token into its header and payload and pretty-prints both as JSON, so you can inspect claims, algorithms and expiry times while debugging authentication flows. Well-known time claims (exp, iat, nbf) are also shown as human-readable dates, with an expired warning when relevant.

Everything happens in your browser — the token is never uploaded, logged or stored, which matters because JWTs often contain session credentials. Note this tool decodes only; it does not verify the signature, so it tells you what a token claims, not whether it's authentic.

How to Use the JWT Decoder

  1. Paste your JWT (a 'Bearer ' prefix is stripped automatically).
  2. Read the decoded header and payload as formatted JSON.
  3. Check the time claims panel for issue and expiry dates.

Features

  • Instant header + payload decoding with pretty-printed JSON
  • Human-readable exp / iat / nbf dates with expiry warning
  • Handles URL-safe Base64 and missing padding
  • 100% client-side — tokens never leave your device

Frequently Asked Questions

Does this tool verify the JWT signature?

No. It decodes the header and payload so you can inspect them. Signature verification requires the signing secret or public key and should happen server-side.

Is it safe to paste a real token here?

The token is processed entirely in your browser and never transmitted. Still, treat live production tokens like passwords — avoid pasting them on shared machines.

Is the JWT Decoder free?

Yes, the JWT Decoder is completely free with no usage limits. No signup, no account and no installation required.

Is my data safe?

Yes. All processing happens locally in your browser using JavaScript — nothing you type is uploaded or stored on our servers.

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