DEV Community


Discussion on: Stop Guessing: What is a JWT?

stevescruz profile image
Steve Cruz Author • Edited

That is a great question. We keep using the access token (the name our JWT has when we are also dealing with refresh tokens) until it expires. Afterwards we use the refresh token with an authentication service to generate another access token (JWT) so your second assumption is correct.

How does it know that our JWT expired? In the payload we include the iat (issued at) claim with a value that is the date and time of when it was generated. Afterwards this IAT claim is compared with the exp (expiration) claim to determine if it should be accepted. If it is rejected what I wrote above happens.