I've never used them, but IIRC they acquired some third-party client and then just modified them. "Blue Alien" or something like that?

googles

"Alien Blue", at least for the official iOS app.

https://en.wikipedia.org/wiki/Alien_Blue

I dunno what the history of the Android app is.

That being said, they're responsible for what they acquire, just saying that a lot of that might not be developed in-house.