What is JWT Decoder?
JWT Decoder parses and displays JSON Web Tokens (JWT) into readable Header, Payload claims, and Signature verification status according to RFC 7519 specs. JWTs are used for user authentication in modern web applications. The tool decodes Base64URL encoded claims (user ID, roles, exp, iat) without requiring secret keys.
How to use JWT Decoder
Paste your encoded JWT token (eyJhbGciOi...) into the input box. The tool automatically decodes the Header and Payload fields into formatted JSON on the right. The tool checks token expiration status (exp claim), highlighting whether the token is currently active or expired. Copy decoded claims with one click.
Key features
- Instant decoding of JWT Header and Payload claims
- Automatic expiration status check (exp claim vs current time)
- Displays issued-at (iat) and not-before (nbf) date times
- Color-coded payload JSON viewer
- 100% private browser client-side execution
Common use cases
- Debugging OAuth2 and OpenID Connect authentication tokens
- Verifying user permissions and role claims inside API tokens
- Checking token expiration times during frontend integration development
Technical details & standards
The decoder parses the three dot-separated Base64URL parts of the JWT token string, decoding the JSON payloads and evaluating Epoch claim timestamps. All decoding executes 100% client-side in your browser. Secret keys and private tokens are never sent to external servers.
Frequently asked questions
Is it safe to paste production JWT tokens into this decoder?
Yes! Processing happens entirely in your local browser runtime. Zero data is transmitted to external servers.
Is my data safe?
All processing happens entirely in your browser. Your data never leaves your device and is never sent to or stored on a server.
Does it work offline?
Yes. Once the page has loaded, most tools keep working without an internet connection.