Three years ago I posted that Queen Alice was the site I played on when I wanted to play CC without an engine, but had not played there for over a year. I quit playing there about a year before the post because the server went down and I had a couple of tournaments that got wiped out. The site owner appears to have abandoned the site as his last post, as near as I could tell when I visited it the other day, was about 10 years ago! Nevertheless, after several attempts I remembered my old password and logged in just to see what was going on. The forums don't seem to be anywhere nearly as active as they were when I played on the site. The day I dropped by 21 members had been active on the site within the last 5 minutes. By comparison, when I logged in at Lechenicher Schach Server, 28 players had been active in the last 10 minutes. Queen Alice had a total of 968 member visits within the last week, so it appears that the site is still running well enough. I am not sure of the total number of players, but 75 of them are rated over 2400. Of course, that has nothing to do with real ratings and the top player's score is +773 -13 =33. At the time I played engine users were not too prevalent, but that has probably changed. In any case, it still looks like it might be a decent place to play if you are looking for a correspondence game on a good free site.
About six years ago I posted about Chess Hotel, a quick and easy place to sign in and play in real time. As I mentioned on the post, I played 5 or 6 games there which were against very weak opponents. At Chess Hotel you can play regular chess in real time at a various time limits. Fischer Random (chess960) is also available. If you want to register you will receive a free account that keeps you games and statistics.
The other day I visited it for the first time since making that post six years ago and played a several 5 minute plus 3 seconds per move games and did not have to wait for more that 30 seconds for the game to be accepted. As a guest you're assigned a 1200 rating and most of your opponents, also guests, will be in that range. The ratings are meaningless and I played a couple of very bad players, but was pleasantly surprised to play several who were quite challenging.
Both sites appear to be in good working order and if you are looking for free site then either Queen Alice for correspondence or Chess Hotel for real time both seem decent choices. The following 5-minute plus 3 seconds per move played on Chess Hotel turned out to be quite interesting.