JWT Debugger
A professional suite of zero knowledge utilities. Edit, parse, format, and encrypt massive data files locally. No server processing. No external API telemetry. Your data never leaves your browser.
Encoded Token
Header
Payload
What is a JSON Web Token (JWT)?
JSON Web Tokens (JWT) are an open, industry-standard method (RFC 7519) for representing claims securely between two parties. JWTs are commonly used in modern web applications for stateless authentication and information exchange. The token itself is a string comprised of three distinct parts separated by dots: the Header, the Payload, and the Signature.
How do JWTs work?
The Header typically consists of two parts: the type of the token (JWT) and the signing algorithm being used (such as HMAC SHA256 or RSA). The Payload contains the "claims"—statements about an entity (typically, the user) and additional data like expiration times or roles. Finally, the Signature is used to verify the message wasn't changed along the way. While the Header and Payload are Base64Url encoded, they are not encrypted. Anyone can decode and read them, which is why you must never put secret information in the payload.
The Danger of Online JWT Debuggers
A massive security flaw in the workflow of many developers is pasting their application's JWTs into remote, server-based decoders online. JWT payloads frequently contain Personally Identifiable Information (PII) such as email addresses, user IDs, or internal routing URLs. Pasting these into a random website exposes your proprietary data to third-party logs.
Our JWT Debugger is 100% Client Side. Powered by local WebAssembly, we decode the JWT entirely in your browser's memory. No telemetry. No server requests. Absolute privacy.