Ascii Generator 2 - Ascii Generator 2 (Ascgen2) is an application to convert images into high quality ASCII art - text...
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
Playscii - Full-featured ASCII art and graphic editor and game creation tool
draw.io - Online diagramming application
ASCII Art Maker - A program for creating ASCII graphics from images and text.
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.