What is JWT Decoder?
A JWT (JSON Web Token) is a base64url-encoded header.payload.signature triplet. This decoder splits and pretty-prints the header and payload locally so you can inspect claims and expiry.
How to use
- Paste your JWT.
- Read decoded header and payload.
- Check the exp / iat hints.
Example
Use this sample to confirm what JWT Decoder does before pasting your own data.
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjMiLCJuYW1lIjoiQWRhIn0.signature
Header: {"alg":"HS256"} | Payload: {"sub":"123","name":"Ada"} Signature is shown but not verified — verification needs the issuer key.
When to use it
Use JWT Decoder for quick local checks, debugging, documentation prep, and one-off conversions where opening a full IDE or command-line workflow would be slower. For production-critical data, always review the output before committing or shipping it.
Frequently asked questions
Does this verify the JWT signature?
No. Signature verification needs the issuer's key. Decoding is local-only for safety.
Is my token uploaded anywhere?
No. Decoding runs in your browser. Always rotate any token you paste into web tools.
What claims should I worry about?
exp (expiry), iat (issued at), nbf (not before), iss, aud and sub — they govern token validity and intent.