JWT Decoder
Decode JSON Web Tokens locally without sending them to a server.
Runs in your browser
Your files and text are processed locally in your browser and are not uploaded.
About JWT Decoder
A JWT Decoder decodes the Base64Url encoded parts of a JSON Web Token to reveal the human-readable JSON header and payload. It does not validate the cryptographic signature, making it a purely observational tool for debugging authentication tokens.
Definition: JSON Web Token (JWT)
An open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object, typically used for authentication and authorization.
Inputs and Outputs
Required Inputs
- Encoded JWTA standard JWT string consisting of three parts separated by dots (Header.Payload.Signature).
Expected Outputs
- Decoded HeaderThe token type and signing algorithm.
- Decoded PayloadThe claims or data contained within the token.
Who Uses the JWT Decoder?
Authentication Debugging
Inspect tokens returned by an OAuth provider to verify the user ID, roles, and expiration timestamp.
Security Auditing
Verify that sensitive information (like passwords) is not inadvertently exposed in the token payload.
How to Use the JWT Decoder
- 1Paste your JWT string into the input area.
- 2The tool will automatically decode the Header and Payload sections.
- 3Review the formatted JSON output.
- 4Use the copy buttons to extract specific claims or headers.
Quick Facts
Privacy & Security Guarantee
Tokens are decoded locally. We do not log, verify, or transmit your JWTs.
Frequently Asked Questions
Does this tool verify the JWT signature?
No, this tool only decodes the Base64Url payload. It does not require your secret key and does not verify the signature's validity. For an in-depth breakdown of token components, registered claims, and signature verification pitfalls, read our developer guide on [JWT structure explained](/guides/jwt-structure-explained).
Is it safe to paste my production JWT here?
Yes. The decoding happens entirely locally in your browser using JavaScript's atob() function. The token is never sent to our servers.