Plotly - Low-Code Data Apps
Dia - Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license.
RAWGraphs - RAWGraphs is an open source app built with the goal of making the visualization of complex data...
draw.io - Online diagramming application
CanvasJS - HTML5 JavaScript, jQuery, Angular, React Charts for Data Visualization
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.