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.