Here is my modest list of cubing apps I use, I would love to hear your suggestions! (I can update this post with new suggestions, turning it into a curated list)

Web:

• Shared online timer: https://www.letscube.net/ [source]
• Alg trainer: https://tao-yu.github.io/Alg-Trainer/ [source]
• Algs + trainer: https://jperm.net/
• Roux algs + tutorials: https://sites.google.com/view/kianroux/home

Android:

• Timer + OLL/PLL trainer: https://play.google.com/store/apps/details?id=com.aricneto.twistytimer [source]

Desktop:

• Timer: https://dallasmcneil.com/projects/blockkeeper/ [source]