How Do You Log Someone Out of a Stateless System? JWT Invalidation on Logout

JWTs are one of those technologies that feel wonderful right up until you hit your first "log me out" requirement. Then you discover the awkward truth: the very property that makes JWTs attractive — statelessness — is also what makes logout hard. This post walks through what JWTs actually are, why "invalidating" one is a design problem rather than a one-liner, and the practical methods available to revoke an access token on logout, along with the bottleneck each one introduces. A quick refresher on JWTs A JSON Web Token (JWT) is a signed, self-contained token. It carries a JSON payload of claims — who the user is, when the token was issued, when it expires, and often a unique token id ( jti ) — and a cryptographic signature over that payload. Because the token is signed with a secret (or a private key), any server holding the corresponding key can verify it is authentic and untampered without calling a database . That last part is the entire point. When a request arrives with a JWT, the server checks the signature and the expiry, reads the claims, and proceeds. No lookup, no shared session store, no round trip. This is what people mean when they call JWT auth stateless : the server keeps no per-user session record. The token itself is the session, and it's valid until it expires. Access tokens and refresh tokens In practice you rarely use a single token. The common pattern splits responsibility across two: The access token is the short-lived workhorse. It's sent on every API request and typically expires in minutes (5–15 is common). Because it's checked statelessly on every call, you want its lifetime short — if it leaks, the damage window is small. The refresh token is long-lived (days or weeks) and does one job: obtain new access tokens when the current one expires. It is not sent on every request — only to a dedicated token endpoint. This lets the access token stay short and stateless while the user avoids logging in every ten minutes. The refresh token is easy —