TreeSheets: Free-Form Data Organizer
TreeSheets

          
            A "hierarchical spreadsheet" that is a great replacement for spreadsheets, mind mappers, outliners, PIMs,
              text editors and small databases.
            Suitable for any kind of data organization, such as todo lists, calendars,
              project management, brainstorming, organizing ideas, planning, requirements
              gathering, presentation of information, etc.
            
            It's like a spreadsheet, immediately familiar, but much more suitable
              for complex data because it's hierarchical.
               It's like a mind mapper, but more organized and compact.
               It's like an outliner, but in more than one dimension.
               It's like a text editor, but with structure. 
            Have a quick look at what the application looks like on the
              screenshots page, see how easy it is to use in the
              tutorial, then give it a download (above).
              A video someone made (on Linux) 
            TreeSheets is exceptionally small & fast, so can sit in your system
              tray at all times: with several documents loaded representing the equivalent
              of almost 100 pages of text, it uses only 5MB of memory on Windows
              7 (!)
            TreeSheets is free & open source. Enjoy!
            Join the
              Discord or
              google group for discussion.
              Grab the source code from
              GitHub, or file bug reports there / feature requests there.
              The past donations page.
              contact the author (Wouter van Oortmerssen) personally.

            

          
        