draw.io - Online diagramming application
BoardEffect - BoardEffect is a board meeting software helps boards prepare for and hold the board meeting efficiently.
Penpot - Design freedom for teams
Azeus Convene - Don’t just meet — Convene. The Smart, Simple, and Secure Board Portal Software.
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.
OnBoard - OnBoard’s board intelligence platform simplifies complex board processes to make board meetings more effective.