Expiresin

Expires_in is a field used in many API authentication schemes to indicate the duration, in seconds, until a token expires. It is most commonly seen in OAuth 2.0 and OpenID Connect token responses, where a server returns an access token along with expires_in to tell the client how long the token remains valid.

While expires_in conveys a relative lifetime, it is distinct from the exp claim in JWTs, which encodes the exact expiration timestamp as a numeric value. Expires_in is typically calculated from the time the token is issued, rather than a fixed clock time.

Usage and considerations: clients use expires_in to schedule refresh operations, renew tokens before expiry, and handle clock skew. It is not a guarantee of continued validity; servers may revoke tokens earlier or extend lifetimes.

Typical values vary by provider and risk model; common lifetimes include 300, 900, or 3600 seconds (5 minutes, 15 minutes, 1 hour). Some services offer longer lifetimes or use rotating tokens.

Practical notes: always validate tokens on the server side; if an exp claim is present, prefer it for client-side expiry checks. Transmit over TLS, and implement token rotation and revocation strategies.