alt/repo
alternative-repository
Labs

JWT Decoder

Instantly decode JSON Web Tokens. Paste a token below to view its header, payload claims, and signature.

100% Local & Offline. Your token never leaves your browser.
Invalid JWT format. Must contain 3 dot-separated Base64URL segments.
Header (Algorithm & Token Type)
{}

Payload (Data & Claims)
{}
Signature
Note on verification: This tool only decodes the token structure. The signature string is displayed above, but you cannot mathematically verify its authenticity or guarantee the payload hasn't been tampered with without the issuing server's secret key.

FAQ

A JWT (JSON Web Token) decoder is a developer tool used to parse and read the contents of authentication tokens. This tool decodes standard JWT formats without requiring server communication.

What is a JWT token?

A 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.

How does JWT work?

In authentication, when the user successfully logs in, a JSON Web Token is returned. This token consists of three parts: a Header (algorithm type), a Payload (user data/claims), and a Signature (to verify authenticity). The client sends this token in the Authorization header of future HTTP requests.

Can you decode a JWT without a secret?

Yes, you can easily decode the Header and Payload of a JWT without the secret key. JWTs are Base64URL encoded, not encrypted. However, you cannot verify the Signature or ensure the data hasn't been tampered with unless you have the secret key.

How to decode a JWT token locally?

You can decode a JWT locally using this tool, which runs entirely in your browser without communicating with a server. Alternatively, you can write a simple script in languages like JavaScript or Python to Base64URL decode the token strings offline.