draw.io - Online diagramming application
asciiflow - Infinite ASCII diagrams, save to Google Drive, resize, freeform draw, and export straight to text/html.
Automatic Organizational Chart Generator - Turn your Excel employee list into an Org Chart with Photos!
PabloDraw - PabloDraw is an Ansi/Ascii text and RIPscrip vector graphic art editor/viewer with multi-user capabilities.
LibreOffice - Draw - Draw, LibreOffice, ODF, open standards, creative software, vector drawing
JavE - JavE (Java Ascii Versatile Editor) is a free Ascii Editor.