JWT Decoder & Debugger
What is a JSON Web Token (JWT)?
JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. JWTs can be signed using a secret (with the HMAC algorithm) or a public/private key pair using RSA or ECDSA.
Why Use Our JWT Debugger?
JWTs often contain sensitive user information or authentication credentials. Unlike many online tools that send your token to a server, our tool parses, decodes, and verifies the JWT entirely within your browser using client-side JavaScript. Your token never leaves your device.
How to Use
- Paste Token: Paste your raw JWT string into the input area.
- Inspect Payload: Instantly view the decoded header (algorithm type) and payload (claims and data).
- Check Expiry: The tool automatically calculates and displays whether the token is expired or how long it is valid for.
- Verify Signature: Enter your secret key (for HS256 tokens) to verify that the token has not been tampered with.
Glossary
- Header
- The first part of a JWT, which typically consists of two parts: the type of the token (JWT) and the signing algorithm being used, such as HMAC SHA256 or RSA.
- Payload
- The second part of a JWT containing the claims. Claims are statements about an entity (typically, the user) and additional data.
- Signature
- The third part of a JWT, created by taking the encoded header, the encoded payload, a secret, and the algorithm specified in the header.