JWT Decoder
Decode and inspect JSON Web Tokens instantly. Verify payloads and check expiration status.
Decoded locally in your browser. PixelTrim never stores or transmits your tokens.
Paste your token on the left
to see the decoded results.
The Professional Guide to JSON Web Tokens (JWT): Debugging and Inspection
In the modern landscape of web security, JSON Web Tokens (JWT) have become the industry standard for representing claims between two parties. Whether you are building a React frontend that communicates with a Node.js backend, or integrating with third-party providers like Auth0 or Google, you will inevitably encounter JWTs. PixelTrim’s JWT Decoder is a specialized developer tool designed to help you peek inside these tokens, verify their structure, and debug authentication issues instantly without compromising your security.
!Decoding vs. Verification
A JWT is NOT encrypted; it is only encoded. Anyone can read its contents. While PixelTrim helps you decode and inspect the data, your application must always verify the signature on the server-side to ensure the token hasn't been tampered with.
✓Privacy First Debugging
Many online JWT debuggers log your tokens on their servers. PixelTrim processes everything locally in your browser. Your authentication tokens are never sent over the network, keeping your user sessions secure.
Understanding the JWT Anatomy
A valid JWT always consists of three parts separated by dots:
Defines the token type and the signing algorithm (e.g., HS256, RS256).
Contains the "claims" or data about the user, permissions, and expiration.
Used by the server to verify that the sender is who they say they are.
Key JWT Claims to Monitor
exp (Expiration Time)
The most important claim for debugging. It tells you exactly when the token becomes invalid. Our tool highlights this in red if the token has already passed its validity window.
sub (Subject)
Identifies the user that the token is about. Use this to ensure your authentication logic is identifying the correct user ID.
aud (Audience)
Specifies who the token is intended for. If the audience in the token doesn't match your API's expected audience, the request will be rejected.
Frequently Asked Questions
Can I edit the JWT and re-sign it here?
No. To re-sign a token, you need the private secret key. PixelTrim is a read-only inspection tool designed for safe debugging without needing to input your sensitive secrets.
Why does my token say "Invalid Format"?
A valid JWT must have exactly three parts separated by dots. If your string is missing a part or contains invalid characters, our decoder will flag it as an error.
Is there a size limit for the token?
JWTs are typically small (under 8KB). Our tool can handle much larger tokens, but keep in mind that excessively large JWTs can cause performance issues in your actual applications.