Highcharts - A charting library written in pure JavaScript, offering an easy way of adding interactive charts to your web site or web 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.
C3.js - D3-based reusable chart library that enables deeper integration of charts into web applications
draw.io - Online diagramming application
React D3 Library - The easiest way to use D3.js in React
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.