Userflows
UMLGraph
draw.io
Dia
yEd
OmniGraffle
CollabNet
UMLet
Vim Python IDE
Userflows
Vim Python IDENo features have been listed yet.
UMLGraph - UMLGraph is a professional automated drawing tool that allows the designers the declarative specification and drawing of UML class and sequence diagram.
draw.io - Online diagramming application
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
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.
OmniGraffle - OmniGraffle is for creating precise graphics like website wireframes, an electrical system designs, or mapping out software class.
CollabNet - ArgoUML, free and safe download. ArgoUML latest version: Open-source diagramming application for personal computers. ArgoUML is a program that allows users to create complex and professional diagrams.