https://debiansupport.com/mirrors is the original source of this information.
Not infrequently I need to install a new package in an older Debian instalation and it often takes me two or three clicks into the search to find the information I need, so here they are:
Debian 12 (Bookworm)
Active mirrors:
deb http://deb.debian.org/debian bookworm main contrib non-free-firmware non-free
deb http://deb.debian.org/debian bookworm-updates main contrib non-free-firmware non-free
deb http://security.debian.org/debian-security bookworm-security main contrib non-free-firmware non-free
Debian 11 (Bullseye)
Active mirrors:
deb http://deb.debian.org/debian bullseye main contrib non-free
deb http://deb.debian.org/debian bullseye-updates main contrib non-free
deb http://security.debian.org/debian-security bullseye-security main contrib non-free
Debian 10 (Buster)
Archive mirrors:
deb http://archive.debian.org/debian/ buster main contrib non-free
deb http://archive.debian.org/debian/ buster-proposed-updates main contrib non-free
deb http://archive.debian.org/debian-security buster/updates main contrib non-free
Debian 9 (Stretch)
Archive mirrors:
deb http://archive.debian.org/debian/ stretch main contrib non-free
deb http://archive.debian.org/debian/ stretch-proposed-updates main contrib non-free
deb http://archive.debian.org/debian-security stretch/updates main contrib non-free
Debian 8 (Jessie)
Archive mirrors:
deb http://archive.debian.org/debian/ jessie main contrib non-free
deb http://archive.debian.org/debian-security jessie/updates main contrib non-free
Debian 7 (Wheezy)
Archive mirrors:
deb http://archive.debian.org/debian/ wheezy main contrib non-free
deb http://archive.debian.org/debian-security wheezy/updates main contrib non-free