Todo by Appigo - What sets Todo Cloud apart from your run-of-the-mill to-do and task-list apps is that it is straight-up powerful. It's time to get things done.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Laverna - Laverna is a JavaScript note taking application with Markdown editor and encryption support.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Notezilla - Colorful & powerful sticky notes app for Windows & Phones.
Zenkit To Do - Organize, plan, and collaborate with To Do