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.

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.

Mindmapping

Android: Squid

iOS: Concepts (availble on most platforms now)

Windows: Microsoft Whiteboard

For teaching: Explain Everything

Scheduling

Google Calendar and any compatible calendar app.

For Android the app I use is Business Calendar

Email

Spike

Task management

Amazing Marvin for personal tasks

Asana for team projects and tasks

Flashcards

Anki or Flashcards Deluxe

No particular preference for the above flashcard apps.

Knowledge dump/second-brain/personal knowledge management (PKM)

Roam research

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.