Decode the token with a browser-based JWT decoder and read the exp claim in the payload, which holds the expiry as a Unix timestamp. The decoding runs entirely on your device, so the token is never transmitted.
A JSON Web Token carries claims in its payload, and the standard exp claim is the expiration time expressed as a Unix timestamp, the number of seconds since 1970. If the current time is past exp, the token should be rejected. Decoding the payload lets you read exp and other timing claims like iat, so you can tell whether a token is still valid while debugging.
A JWT is effectively a live credential until it expires, so you should not paste a real one into a site that decodes it server-side. A client-side decoder splits and Base64-decodes the token in your browser, showing the header and payload without transmitting anything. Note that decoding reads the claims but does not verify the signature. It is free and needs no sign-up.
The exp claim holds the expiration time as a Unix timestamp in seconds.
No. The token is decoded in your browser and never transmitted.
No. Decoding reveals the claims; verifying the signature separately requires the signing key.