以前、国内外のアウトラインエディタを調べた。
海外にも結構あるよね

メモ紙 Windows 10/8/7/Vista/XP/2000　
https://www.vector.co.jp/soft/review/winnt/personal/se388286.html
https://www.vector.co.jp/magazine/softnews/170907/n1709071.html

http://kusamura.la.coocan.jp/tools/memogami.html
インストール不要

TreeLine https://www.portablefreeware.com/index.php?id=971

<海外>
CherryTree
https://www.portablefreeware.com/index.php?id=2790
https://www.giuspen.com/cherrytree/

個人用Wiki　OutWiker https://alternativeto.net/software/outwiker/
OutWiker https://www.portablefreeware.com/index.php?id=2797

Flashnote　https://www.portablefreeware.com/index.php?id=2775

EverEdit http://www.everedit.net/
https://www.downloadcrew.com/article/29518-everedit

minipad2　https://www.portablefreeware.com/index.php?id=1500

TreePad　https://alternativeto.net/software/treepad/

Treepad Lite　https://www.portablefreeware.com/index.php?id=1734

The Guide　https://www.portablefreeware.com/index.php?id=1499