Doit.io is described as 'Doit is the new and easy way to get organised. Take notes, manage projects, share ideas, and collaborate - all in one place' and is an app in the Office & Productivity category. There are more than 100 alternatives to Doit.io for a variety of platforms, including Online / Web-based, Windows, Mac, iPhone and SaaS. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Notion or Trello. Other great apps like Doit.io are Microsoft OneNote (Freemium), Evernote (Freemium), Simplenote (Free, Open Source) and CherryTree (Free, Open Source).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.
With so many tools, it's hard to keep everyone on the same page. Notion is a new tool that unifies them all. It's like Google Docs, but everything is organized and discoverable by your team. Real collaboration in real-time.