JWT Token Decoder — Free Online Tool

The JWT Token Decoder splits a JSON Web Token into its three parts — header, payload, and signature — and Base64URL-decodes the first two so you can read the claims. Since a JWT is only encoded rather than encrypted, this is the fastest way to see what a token from an auth flow actually contains.

That last point deserves emphasis because it is misunderstood constantly: anyone holding a JWT can read its payload. Base64 is an encoding, not a secret. The signature guarantees that the token has not been altered since it was issued — it does not hide anything. Putting personal data, internal identifiers, or anything sensitive in a JWT payload is effectively publishing it to whoever has the token, which is a real and recurring mistake in production systems.

What you are usually checking here are the standard claims. exp is the expiry as a Unix timestamp, and an expired token is by far the most common cause of a login that worked five minutes ago and now returns 401. iat is when it was issued, iss identifies who issued it, aud identifies who it was meant for, and sub is the subject, usually a user id. Comparing exp against the current time answers most "why is this request being rejected" questions immediately.

Decoding happens entirely in your browser using local Base64 decoding. The token is never transmitted — which matters, because a valid token is a credential.

Our JWT Token Decoder is completely free to use with no signup required. For this tool, processing runs in your browser — your files and data stay on your device and are not uploaded to our servers.

Whether you are a developer, designer, student, or business owner, this tool is designed to save you time and make your workflow more efficient. Bookmark this page to access it whenever you need it — it will always be free.