Dynalist is a great cross-platform outliner in the spirit of Org Mode for Emacs users, or Omni Outliner for Apple folk. You can make lists, indent them as much as you need (to make a sub-project perhaps?), zoom in and out when you need to focus in on a few points and check off or strike out tasks as necessary. I have tried my best to keep all of my reference information and notes in one application best suited for note taking and my tasks in a task manager but for my taste, mashing everything into one tool has been a boon for my clarity. Dynalist is simple compared to the software I used previously, but it turns out I havenʼt needed those missing features.
You may have heard of Workflowy which is great software, donʼt get me wrong, but Dynalist is open about their development, is generous with their free-tier and pro plan trial and is receptive to their community of customers. I have paid for both, but Dynalist won me over through their continual efforts to improve and grow... and their extensive keyboard shortcuts. Who could forget those!
[Note: The links to Dynalist are referral links, if you sign up using one you get a free month of their pro plan and I get a little off my monthly bill. Itʼs a service I have happily been a paying customer of for months, but this being the Internet, who knows what your feelings towards referrals may be. Consider yourself warned.]