🛡️ JWT Decoder

JWT Decoder is a free, secure, and fully interactive tool that lets you decode and verify JSON Web Tokens (JWTs) right in your browser — with no server-side processing or data collection. Whether you’re debugging a login issue, building an authentication system, or auditing token-based authorization flows, our tool gives you a precise view into the structure and contents of your JWTs.

Every JWT is composed of three parts: a header, a payload, and a signature. With our decoder, you can paste any token and instantly visualize each section. The header and payload are displayed in readable JSON format and also as a structured claims table, making it easy to identify fields like sub, iss, exp, aud, and any custom claims your app may include.

One of the most powerful features of the Plus.Tools JWT Decoder is built-in signature verification. You can validate tokens signed with the HS256 algorithm simply by entering the secret key used to sign them. Our tool will automatically recalculate the token’s signature and tell you whether it matches — helping you quickly determine whether a token is authentic or has been tampered with.

Designed for developers, security engineers, QA testers, and anyone working with identity systems, this tool removes the guesswork from understanding JWTs. Unlike many online utilities, we don’t log your tokens or send data over the internet. All operations are performed 100% in your browser, ensuring your data remains private and secure.

Need more advanced features in the future? We’re actively developing support for other signature algorithms such as RS256 and ES256, as well as options for generating test tokens, inspecting expiration claims, and visualizing JWT lifecycles.

Try out the JWT Decoder now — it’s fast, intuitive, privacy-first, and completely free.