JWT Decoder & Verifier
Decode and inspect JWT tokens instantly. View header, payload, and signature. 100% client-side — your tokens never leave your browser.
About this tool
A JSON Web Token (JWT) consists of three Base64URL-encoded parts separated by dots: the header (algorithm and token type), the payload (claims/data), and the signature. This tool decodes all three parts instantly in your browser without sending your token anywhere.
Use this tool to debug authentication issues, inspect claims (iat, exp, sub, roles), check token expiration, and verify the algorithm being used. Simply paste any JWT and the decoder will display a formatted, color-coded breakdown of every field.
The signature verification tab lets you confirm the token hasn't been tampered with — paste your secret or public key and the tool will validate the signature client-side using the Web Crypto API.
Frequently Asked Questions
Is it safe to paste my JWT here?
Can this tool verify JWT signatures?
What algorithms does it support?
Why does my JWT show 'expired'?
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