JWT Debugger
Decode and debug JSON Web Tokens (JWT) directly in your browser. Client-side only, secure and fast.
JWT Debugger
Decode and debug JSON Web Tokens (JWT) directly in your browser. Client-side only, secure and fast.
About JWT debugging
Decode header and payload only
The debugger splits the token on dots and Base64URL-decodes the first two parts as JSON. It is useful for checking alg, typ, claim names, and payload shape, but it does not display or cryptographically verify the signature segment.
Treat decoded claims as untrusted
JWT contents are only trusted after server-side verification with the correct secret or public key. Use this page for local structure debugging, not for deciding whether a token should grant access.
FAQ
Common questions and answers about this topic.
What is a JWT?
JSON Web Token, a compact URL-safe format for securely transmitting claims between parties. It consists of a header, payload, and signature.
What parts are decoded?
The header and payload are Base64URL-decoded and displayed as JSON. The signature segment is not decoded or verified by this debugger.
Can this verify signatures?
This debugger decodes and displays the token structure. For signature verification, you would need the secret key or public key.
Is my data sent to any server?
No, JWT debugging runs entirely in your browser. Your token is parsed and decoded locally with JavaScript and never transmitted anywhere.