Counting unique visitors without using cookies, UIDs or fingerprinting.

we send a header which is a date set to the beginning of each day:

last-modified: Wed, 30 Nov 2022 00:00:00 GMT

From now on, every time this request is made again, the server receives the date and adjusts it by one second, and returns it to the browser:

last-modified: Wed, 30 Nov 2022 00:00:01 GMT

This way, the server can calculate the distance in seconds since midnight to give us a visit count.