PicoTCP is a free TCP/IP stack implementation

MollenOS/Vali is a modern operating system that is built with focus on abstraction and a modular design, allowing anyone to port it to any architecture. It currently targets the x86-32 and x86-64 platform.

A simple-to-use modular, cross-platform graphics library. It combines the freedom of lower-level graphics libraries with modern C techniques, offering both simplicity and convenience.

MODWM - Modular Dynamic Window Manager

C simple and elegant implementation of an actor library

Modular binary injection framework, successor of libhooker

A realtime scripted modular audio engine for video games and musical applications.

C99 modular IRC bot with markov chains

Block Erasure Format - An extensible, fast, and usable file utility to encode and decode interleaved erasure coded streams of data.

Stealthy x64 thread manipulation library for calling functions inside target processes without creating remote threads or installing hooks.

Simple-to-use single header modular font rendering library written in C.

The modular server

Tiny modular assembler & vm for lightweight control microcode

A lightweight modular C logging library

Build system scripts based on GENie (https://github.com/bkaradzic/genie) project generator tool

A low-cost semimodular analog synthesizer

KOS (Kay-OS) Operating System 400

Modular binary injection framework

NGINX module that implements ACME for automated TLS configuration (Let's Encrypt)

A modern Unix inspired operating system