It used to be ChastiKey. But since the developer of The ChastiKey app retired and was replaced with ChastiSafe, the administration of the Discord server renamed it to Chastity Maze. That’s where I usually hang out.
JakeO doesn't want to lock into a full app because it reduces the speed at which he can do updates (4 in the last 2 weeks). TBH the web page works perfectly fine on PC or mobile for me.
I was initially hesitant at the lack of an app but the web page is fully functional. You can also draw your cards with a discord bot if you don't want the web page open. It's pretty much a continuation of chastikey but they've added some new features.