JWT Expiry Handling: exp Claim and Token Refresh
How to read the exp claim, implement silent refresh, handle clock skew, and degrade gracefully when tokens expire.
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Tags: security, jwt, authentication
JWT Expiry: Access Tokens, Refresh Tokens, and Silent Refresh Token expiry is one of the most important — and most frequently mishandled — aspects of JWT-based authentication. Too long, and compromised tokens remain valid for extended periods. Too short, and users get logged out every few minutes. The solution is a two-token system: short-lived access tokens paired with longer-lived refresh tokens. Why Access Tokens Must Expire An access token that never expires is equivalent to a permanent password. If it's compromised (stolen from localStorage, captured in a log, extracted from a request) the attacker has permanent access to the user's resources — until the user manually changes their password or the service implements full revocation. The primary mitigation is short expiry. If an…
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