draw.io - Online diagramming application
Evercontact - Your contacts always up to date and automatically with Evercontact.
Penpot - Design freedom for teams
CONTACTBOX - CONTACTBOX combines the simplicity of an address book with effective functions of a CRM system.
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.
Pobuca Connect - Connect with your contacts.