Decode a JSON web token.

Debugging authentication usually means staring at a JWT, three base64url segments separated by dots and unreadable until something decodes them. The decoder above splits the token, decodes the header and payload, and prints both as formatted JSON with the signing algorithm visible in the header. When the payload carries exp, iat, or nbf, each one is shown as a readable date alongside whether that date has passed.

A JWT is base64url under the hood, so for anything that isn't a token you can decode Base64 in the browser instead. The payload comes back formatted already, but when the API response around it arrives as one minified line you can clean up minified JSON too.

When you need to share a decoded payload with a teammate while debugging, you can host any file type and send the link rather than pasting JSON into chat. The rest of NudgeHost's free developer tools sit alongside this decoder.

The decoder runs locally and logs nothing, which matters because tokens are sensitive. It's free and needs no signup, and when something does need hosting you can share a file now with nothing to set up.