JWT in Microservices: API Gateway vs Service Validation

Where to validate a JWT with one API gateway and ten microservices, why only the auth server holds the private key, how JWKS key rotation works, and what…

JWT in microservices: common questions

Should I validate a JWT at the API gateway or in every microservice?

Both. The gateway rejects bad tokens early, and each service verifies the token again because requests can reach it without the gateway: internal callers, batch jobs or a misconfigured route. Verification is local and cheap with a cached public key.

Does every microservice need the private key?

No. Only the auth server holds the private key and signs tokens. The gateway and services fetch the public keys from the JWKS endpoint, cache them, and use them only to verify.

What happens to a JWT when the user logs out?

The client deletes it and the auth server revokes the refresh token, so no new access tokens are issued. An existing access token stays valid until it expires unless you add a deny list or token introspection.

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