catchorg/Catch2
A modern, C++-native, test framework for unit-tests, TDD and BDD - using C++14, C++17 and later (C++11 support is in v2.x branch, and C++03 on the Catch1.x branch)
zeux/meshoptimizer
Mesh optimization library that makes meshes smaller and faster to render
LibreCAD/LibreCAD
LibreCAD is a cross-platform 2D CAD program. It can read DXF/DWG, and write DXF/DWG/PDF/SVG files. It supports point/line/circle/ellipse/parabola/hyperbola/spline primitives. The GUI is highly customizable, and has dozens of translations.
ocornut/imgui
Dear ImGui: Bloat-free Graphical User interface for C++ with minimal dependencies
carbon-language/carbon-lang
Carbon Language's main repository: documents, design, implementation, and related tools. (NOTE: Carbon Language is experimental; see README)
facebookresearch/faiss
A library for efficient similarity search and clustering of dense vectors.