Best open-source C++ projects

An Unreal Engine 5.7 editor plugin that embeds the Claude Code CLI as an in-editor chat panel and exposes 20+ MCP tools for editing actors, Blueprints and levels.

Native C++20 desktop terminal for financial research, with Qt6 UI, embedded Python analytics, AI agents and 100+ market data connectors.

Windows desktop app and CLI that enhances images and videos on NVIDIA RTX GPUs using DLSS 5 neural rendering, upscaling, frame generation, and color tools.

A free, open-source C++ game engine for Windows, with source code in Git and no royalties or fees for any use, including commercial.

An experimental pattern-based DAW where one pattern can be edited in a tracker, piano roll or step grid, with CLAP, VST3 and SoundFont support.