Pendo - Pendo helps product teams understand and guide users to create product experiences that customers love.

Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.

Sitecore - Sitecore A/S has produced the Sitecore content management system since 1999.

draw.io - Online diagramming application

Kustomer - Kustomer is the first intelligent CRM for customer experience that enables you to know everything about every customer.

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.