JWT Decoder
Decode and inspect JSON Web Tokens instantly. View headers, payload, and expiration without sending data anywhere.
Secure & Private
All decoding happens in your browser. No data is sent to any server.
Real-time Validation
Instant feedback on token structure and validity as you type.
Developer Friendly
Clean interface with copy buttons and formatted JSON output.
What is a JWT Decoder?
A JWT (JSON Web Token) decoder is a tool that parses and displays the contents of a JWT without needing the secret key. JWTs are compact, URL-safe tokens used to represent claims between two parties — typically for authentication and authorization in web applications and APIs. Each token consists of three Base64URL-encoded parts separated by dots: the header (algorithm and type), the payload (claims/data), and the signature (verification hash).
Common Use Cases
- Inspect the claims inside a JWT received from an OAuth or OpenID Connect provider
- Debug authentication issues by checking token expiry (
exp) and issued-at (iat) fields - Verify the algorithm (
alg) used to sign a token during a security review - Quickly check which roles or scopes are embedded in an access token
- Validate token structure when integrating with a third-party identity provider
How It Works
The decoder splits your token on the . separator and Base64URL-decodes each segment. The header and payload are then parsed as JSON and pretty-printed. The signature is displayed as-is because verifying it requires the secret key or public certificate — which never leaves your machine when using this tool. All decoding happens entirely in your browser; the token is never sent to any server.
Frequently Asked Questions
Is it safe to paste a JWT into this tool?
Yes. Decoding runs entirely in your browser using JavaScript — nothing is transmitted to a server. That said, avoid pasting production tokens containing sensitive data into any online tool as a best practice.
Can this tool verify the JWT signature?
No. Signature verification requires the secret key (HMAC) or public key (RSA/ECDSA), which you should never share with a third-party tool. This decoder only reads the payload claims.
What does "token expired" mean?
The exp claim is a Unix timestamp indicating when the token stops being valid. If the current time is past that timestamp, the token is expired and will be rejected by most servers.
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What is a JWT? JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.
This tool decodes the token structure but does not verify the signature. Always validate tokens server-side.