JWT Decoder

The JSON Web Token (JWT) Decoder is a client-side debugging tool that safely unpacks and pretty-prints the Base64Url-encoded Header and Payload sections of a JWT. It enables developers to inspect token claims (like user IDs, roles, and expirations) instantly.

Because the decoding happens 100% locally in your browser logic with no backend involvement, it is completely secure to paste production tokens here. You never have to worry about your sensitive session tokens being logged by a third-party server.

Decode your web tokens securely:

1. Paste your complete, three-part JWT into the large input area.
2. The tool instantaneously parses the token and decodes the Base64 chunks.
3. View the pretty-printed JSON Header (which shows the signing algorithm).
4. View the pretty-printed JSON Payload (which shows the data claims).
5. Note: This tool decodes data for viewing; it does not perform cryptographic signature validation.

JWTs are the backbone of modern web authentication and authorization:

• Authentication Debugging: Verify that your OAuth/OIDC login flow is successfully embedding the correct user claims (email, ID) within the token payload.
• Expiration Checks: Inspect the 'exp' (expiration time) and 'iat' (issued at) claims to debug session timeout and refresh token issues.
• Role-Based Access Control: Confirm that specific role matrices or permission scopes are correctly serialized into the token by the backend.
• Security Auditing: Check headers to ensure tokens are securely using the expected signing algorithms (like RS256 instead of 'none').