Zim brings the concept of a wiki to your desktop. Store information, link pages and edit with WYSISYG markup or directly typing some lightweight markup syntax and see it previewed as-you-type. Creating a new page is easy by either clicking on the "Create new note"...
Org mode is for keeping notes, maintaining TODO lists, planning projects, and authoring documents with a fast and effective plain-text system.
MyTetra is open source and cross platform personal manager for information accumulation. It is powerful program for data memorization and structuring notes.Discontinued
"Last actual version: 1.43.27 at 06.07.2018": https://webhamster.ru/site/page/index/articles/projectcode/138
TaskOnPaper is a powerful and at the same time an intuitive tool for creating to-do lists. Enter your plans and goals, group them into projects and edit them as easily as on paper.