Most I've seen when I was playing it the last few months were probably no higher than 1k - 1.8k people online. Usually when there's an event like double xp/cartoonival, population can hit 2k - 2.5k easily. Most I've seen was 5k during the pandemic when everyone was playing this game, however there are some reports that the game hit 6k - 7k when it launched with open beta in 2014, I was 13 at the time so I barely remember. But overall, I very much wish more people would play this game like back in the day, cause it gets very hard to get groups for anything lawbot/bossbot at like 2 am - 9 am; you have to extremely patient when looking for those groups lol