Best open-source C projects

SDK for converting trained AI models to RKNN format and running inference on Rockchip NPU boards via Python and C APIs.

Open-source vector similarity search extension for Postgres, storing and querying embeddings alongside your relational data.

An in-memory data store used as a cache, data structure server, document store, vector database, and message broker.

Open-source iOS and macOS compatibility layer that runs your own Switch copy of Diablo II: Resurrected with Reign of the Warlock natively on iPhone, iPad and Mac.

Fast, open-source static analysis CLI that finds bugs and enforces coding standards using code-like patterns instead of regex or ASTs.

An open source photography workflow application and non-destructive raw developer for managing, editing and exporting digital negatives.

An open-source, 3D-printable mini quadruped robot built on the ESP32 with an OLED face and servo-driven walking.

A Task Manager replacement for Windows and Linux that shows deep per-process detail such as threads, memory, handles, sockets and modules.

Zen C is a systems language with high-level ergonomics that compiles to readable GNU C11 and runs with C-level performance.

A shell-like, text-based terminal file manager where you manage files by typing commands instead of using a TUI or GUI.

A narrow native inference engine for running DeepSeek V4 Flash and other selected large models on consumer Metal, CUDA and ROCm hardware.

Open-source, community-built e-reader firmware for ESP32-based e-ink devices, focused on EPUB reading and easy customization.

An ESP32 desk display that shows your Claude Code usage limits, with an animated mascot that reacts to prompts and alerts you when a session needs input.

A lightweight Windows tool that configures Windows Filtering Platform rules to control which apps can use the network.

A teaching operating system with about 2,000 lines of C and RISC-V assembly, designed so students can read all of its code.

A Windows and macOS virtual machine app for running sandboxed full desktop VMs with GPU acceleration, usable from a GUI or a scriptable API.

Lets an AI vision model operate a real iPhone using a $7 ESP32-S3 board that acts as an AirPlay screen receiver and USB HID mouse, with no computer needed at run time.

A fast, multi-threaded command-line string search tool that is grep-compatible, with SIMD acceleration and regex support.

An open-source MPP database for data warehousing and large-scale analytics, built on a newer PostgreSQL kernel as a successor to Greenplum.

A Linux kernel framework that lets you build virtual PCIe devices in userspace and test host drivers against them without real hardware.