1. Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.

    freemium $12.5 / Monthly (Per user - Business Class)

  2. Todoist is a to-do list that helps you get organized, at work and in life.

  3. Collaborate with your team and share the data you care about in one place

  4. The simplest way to keep notes. Light, clean, and free. Simplenote is now available for iOS, Android, Mac, and the web.

  5. MemPad is a plain text outliner and note taking program with a structured index.

  6. wikidPad is an application for storing thoughts, ideas, todo lists, contacts, or anything else that user can think of to write down.

  7. Lifetick is an online Goal Setting application with a stylish, easy to use interface.

  8. A beautifully crafted outliner for your Mac:

  9. Tkoutline is a single pane, cross-platform outline editor written in Tcl/Tk .

  10. Cross-platform app for Mac, iPhone, iPad, and iPod Touch.

  11. Scrivener is a content-generation tool for composing and structuring documents.

  12. Wunderlist is the easiest way to get stuff done. Whether you’re planning a holiday, sharing a shopping list with a partner or managing multiple work projects, Wunderlist is here to help you tick off all your personal and professional to-dos.