About
Built for developers
who value privacy
JWT Decoder is a free, client-side JSON Web Token inspection tool. We believe developer tools should be fast, honest, and respect your data — no accounts, no analytics, no token ever leaves your machine.
Our Mission
The web is full of "free" tools that quietly harvest the data you paste into them. We built JWT Decoder because we wanted something different: a genuinely private, zero-dependency token inspector that lives entirely in your browser.
Every decode operation runs in your JavaScript runtime. Nothing touches a network. There are no user accounts, no telemetry SDKs, and no advertising. That's a promise, not a policy page footnote.
What We Stand For
Privacy by Default
All token processing happens locally in your browser. Your JWT never reaches our servers — because we don't have servers doing anything with it.
Speed First
Decoding a JWT takes microseconds. We keep the interface lean so results are instant, with no loading spinners or round-trip latency.
Transparency
We explain what every claim means, what every algorithm does, and what our tool can and cannot verify — no black boxes.
Developer-Centric
Syntax highlighting, one-click copy, expiry timers, and a claims inspector — designed by developers for the daily debugging workflow.
Accessible
Semantic HTML, ARIA labels, keyboard navigation, and mobile-responsive layout — usable by everyone, on every device.
Standards-Compliant
Fully aligned with RFC 7519 (JWT), RFC 7515 (JWS), and RFC 7518 (JWA). We document algorithm support honestly.
Technology Stack
Why Another JWT Tool?
There are many JWT decoders online. Most of them log your tokens server-side, serve ads, or bundle heavy JavaScript frameworks for a task that requires exactly zero server calls. We disagree with that approach.
JWT Decoder loads fast, works offline once cached, and never asks for a login. The entire decoding logic fits in a single JavaScript function — you can inspect it in DevTools right now.
What We Can and Cannot Do
We can decode and display the header and payload of any syntactically valid JWT. We can detect standard registered claims (sub, iss, aud, exp, iat, nbf, jti) and show human-readable timestamps and expiry status.
We cannot verify a token's signature without the secret key or public certificate — and we never prompt you for those credentials. Signature verification should happen in your backend using a trusted library like python-jose, PyJWT, or jsonwebtoken.
Get in Touch
Have a feature request, found a bug, or just want to say hello? Head over to our Contact page and drop us a message. We read everything.
Ready to decode a token?
Paste your JWT on the home page — results appear instantly.