Aseprite is one of the most popular. Photoshop/gimp can also do pixel/sprite graphics. And the old ImageReady photoshop side tool has a timeline for animations.
There is also Tiled, all those would be the major ones. I use mainly Gimp and Aseprite myself, but not really for animations because I lay out all animations frame by frame in my sprite sheets.
Viewing post in Sprite making
Not sure that its available on android or iOS devices. Digging a bit it seems there's versions for major platforms like windows, mac, and linux, and even a plugin for touchscreens, but that only seems to support windows variants like Surface, Surface Book, Surface Go. Apparently in the pipeline for future versions, but thats down the pipeline. There does seem to be a bit of a community hack floating around, but you can also find some alternatives to Aseprite for android here.