nbf — Not Before

Location: payload · Format: timestamp

Unix epoch seconds before which the token must not be accepted, used to pre-issue a token that only becomes valid later. Same milliseconds-vs-seconds pitfall as exp, and the same small clock-skew leeway should apply.

Defined in RFC 7519 §4.1.5.

Decode a JWT and inspect its nbf claim in the TokenPrism debugger — free, entirely in your browser.