For developers, who are building real-time data-driven applications, Redis is the preferred, fastest, and most feature-rich cache, data structure server, and document and vector query engine.

The PHP Interpreter

Command-line JSON processor

build-once run-anywhere c library

Embedded web server, with TCP/IP network stack, MQTT and Websocket

tiniest x86-64-linux emulator

A completely-from-scratch hobby operating system: bootloader, kernel, drivers, C library, and userspace including a composited graphical UI, dynamic linker, syntax-highlighting text editor, network…

Lightweight Ruby

The seL4 microkernel

canonical libwebsockets.org networking library

A standalone and lightweight C library

A portable device that can spoof/emulate any magnetic stripe, credit card or hotel card "wirelessly", even on standard magstripe (non-NFC/RFID) readers. It can disable Chip&PIN and predict AMEX car…

Stores your data in ICMP ping packets

The Rubinius Language Platform

Airtunes emulator! Shairport is no longer maintained.

luna programming language - a small, elegant VM implemented in C

A fast streaming JSON parsing library in C.

An eventing framework for building high performance and high scalability systems in C.

The Scalable TLS Unwrapping Daemon

An operating system written in JavaScript

gperftools for ruby code

An implementation of markdown in C, using a PEG grammar

A tiny subset of Ruby with a Lua'esc VM

A new language for the web

subset-of-C compiler targeting 32-bit x86

An implementation of /dev/kvm for Mac OS X

Ruby wrapper for POSIX IPC message queues.

An extension to PostgreSQL allowing Kyoto Cabinets to be used as a backing data store.

📺 A cross-platform immediate mode user-interface library. Public domain.

A minimal replacement for BlueZ, for use with Bluetooth keyboards and mice on Linux. Uses BTstack, doesn't require kernel support, BlueZ, DBus...