It happens. I was just checking it, seemed OK, had a number of new updates, when it suddenly went down. It has happened before.
It's not cheap to keep a high-traffic website such as this. The maintainer estimates it will cost about one thousand dollars PER MONTH, and therefore they will likely need to resort to ads. But they are also offering a lifetime no-ads subscription for a one-time donation of... I can't look it up right now since the site is down, but it's not an unreasonable amount.