// free-toolJWT → JSON
JWT Decoder
Paste a JSON Web Token and see its header and payload decoded into formatted JSON, with the timestamp claims (iat, exp, nbf) translated into readable dates and a clear expired / valid indicator. Decoding is pure Base64 — the token never leaves your browser, and the signature is not (and cannot be) verified without the secret.
no signup · no watermark · unlimited use
Frequently asked questions
Is it safe to paste a real token here?
The token is decoded locally and never transmitted — nothing leaves your browser. Still, treat production tokens as secrets: prefer expired or development tokens when possible.
Does this verify the signature?
No — signature verification requires the signing secret or public key. This tool decodes the (Base64-encoded, unencrypted) header and payload, which is what you need for debugging claims.
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Need custom tools like this in your product?
I build fast, privacy-first web applications with Next.js — these converters run entirely in the browser, and yours can too.