The following are apps that I commonly use and am asked about.
While apps can be incredibly helpful, over the years of using different productivity and learning apps, I've realised that more productivity apps do not mean more productivity. Some of the most popular apps for learning are terrible at actually facilitating learning.
I am more productive and efficient now than ever before and my app stack is smaller than ever too. Don't get sucked into the illusion of productivity.
Scheduling, setting up apps, rearranging tasks... none of these actually get work done.
Build a conceptually sound system and find the apps to fit your needs.
Don't build your system around an app's features. This is a very easy way to derail your true productivity and self-management.
With that out of the way, here are the apps.
iOS: Concepts (availble on most platforms now)
Windows: Microsoft Whiteboard
For teaching: Explain Everything
Google Calendar and any compatible calendar app.
For Android the app I use is Business Calendar
Amazing Marvin for personal tasks
Asana for team projects and tasks
Anki or Flashcards Deluxe
No particular preference for the above flashcard apps.
Knowledge dump/second-brain/personal knowledge management (PKM)
Notion is also acceptable, as is RemNote or Obsidian
Another app that the community has found very useful in reducing screen time (especially on the phone).
Clearspace (iOS app + chrome extension) - You can find android alternatives on Google Play store.