Decode JSON Web Tokens Instantly
JSON Web Tokens (JWT) are the standard for stateless authentication in modern web applications, but they look like gibberish to the human eye. Our JWT Decoder allows you to paste any JWT string and instantly view its decoded Header, Payload (Claims), and Signature.
Essential for Authentication Debugging
When a user's session mysteriously fails, the JWT is the first place to look. Our tool helps you instantly verify:
- Expiration (exp): Automatically translates the `exp` and `iat` (issued at) Unix timestamps into human-readable dates so you can see if the token has expired.
- User Roles: Easily view custom claims (like `user_id` or `role`) to ensure the server generated the token with the correct permissions.
- Algorithm (alg): Verify the signing algorithm (e.g., HS256, RS256) used in the token header.
Security Note
A standard JWT is encoded (Base64), not encrypted. Anyone can decode and read the payload. The signature only prevents tampering, it does not hide the data. Never put sensitive info (like passwords) in a JWT payload.
How to Use This Tool
- Upload or Input Data: Select your file or paste your data directly into the tool interface. Everything remains on your device.
- Configure & Process: Adjust any optional settings if necessary. The tool will process your data instantly inside your browser.
- Download Result: Preview the output and click the download or copy button to save your final results.
Frequently Asked Questions
Will this verify the signature?
Currently, the tool acts as a decoder to let you read the payload. Signature validation (which requires the server's secret key) must be done on your backend.
Is my token safe here?
Yes! The token is decoded entirely locally in your browser using JavaScript. We do not log or transmit your authentication tokens.
Why is the payload empty?
Ensure you have pasted the full token, which consists of three parts separated by dots (header.payload.signature).