Hermet.dev

Developer tools that never phone home.

JWT Decoder

Read a token’s header and claims, and see whether it has expired — without handing a live credential to a server.

Note: decoding only reads the token. The signature is not verified here — a decoded token proves nothing about who issued it. Times are computed from your own clock.

Runs 100% in your browser. A JWT is a live credential. Decoding it here means it never transits a network or lands in someone’s logs.

Your input never leaves this page — there is no Hermet server to send it to, and nothing you paste is saved anywhere. Reload with your browser’s Network tab open and watch: no request carries your data, because no request is made at all.