Skia - Skia is an easy-to-use and user-friendly 2D Graphics Library that comes with many prominent APIs for usage in software and hardware platforms.
Cairo - Cairo is an open-source 2D graphics library released under the GNU Lesser General Public License with support for several output devices.
PlotDevice - PlotDevice is a graphics language for tinkerers, designers, developers and is written in Python.
Bgfx - Bgfx is an open-source, high-performance, and cross-platform graphics API agnostic style rendering library that gives you the tools to create high-profile video games without limitations.
SkiaSharp - SkiaSharp is a simple yet robust, cross-platform 2D graphics API designed from scratch for .NET platforms based on Google’s Skia Graphics Library.
Raphael - Raphael.js is an Object Oriented drawing library. It is good at making in-depth diagrams with complex interactions.