JWT Decoder & Debugger Online Free
Decode and inspect JSON Web Tokens. View header, payload, and signature instantly.
How to Use JWT Decoder
- 1
Paste your JWT token into the input area.
- 2
Header, payload, and signature are automatically decoded.
- 3
Check expiry, issuer, and custom claims at a glance.
About JWT Decoder
Decode JSON Web Tokens instantly with our free online JWT decoder. JWTs are the standard for modern API authentication, but their opaque format makes debugging tricky. Paste any JWT and immediately see the decoded header, payload, and signature. Expiry timestamps are converted to human-readable dates. Tokens are never transmitted or logged. Decoding happens entirely in your browser via Base64URL decoding.
Built by
Fateh Raiyan IshmumFull-stack dev since 2020. Full-stack web developer since 2020. Builds privacy-first, open-web tools. Specialises in Next.js, TypeScript, and performance-focused design.
Frequently Asked Questions
A JSON Web Token is a compact, URL-safe token consisting of three Base64-encoded parts: header, payload, and signature. Widely used for authentication and API authorization.
No. This tool only decodes the token. Signature verification requires the secret or public key and should be done server-side.
Never. All decoding happens in your browser. Your token and its claims are safe.
Only if the signing key is compromised. The signature protects against tampering. But anyone can read the payload, so never store secrets in a JWT.