Specifies a UNIX timestamp in seconds after which the request will no longer be served.
For each request the expires parameter value will be compared with the current time. If the value is in the future the request will be processed successfully and the Cache-Control header will return a value for max-age according to the remaining time specified in the expires parameter.
If the expires parameter value references a UNIX timestamp that is in the past, a 403 Forbidden HTTP error will be returned.
expires parameter should be used in conjunction with secure sources and signed requests. Otherwise, expires value could be tampered with.
Examples
Assuming the current date and time is 2020-11-22 17:00:00 UTC and we want the URL to expire in one hour, we would need to transform 2020-11-22 18:00:00 UTC into a UNIX timestamp in seconds. That value is 1606068000 so we need to use the parameter expires=1606068000:
https://assets.imglab-cdn.net/flowers.jpeg?width=500&expires=1606068000&signature=g4SM-sEetgS5WNL-C_eiOPDlC75jt2ihHg3yf4lUPtc