Gibber is a live coding environment for the web browser, using the Gibberish.js audio engine, the CodeMirror code editor library and wrapping Three.js for 3d graphics and shader support. Version 2 of Gibber features a much more efficient audio engine, some interesting mapping abstractions and a server/database backend for publishing and browsing files and collaboratively live coding.

TidalCycles (or Tidal for short) is a language for live coding patterns.
It allows you to make musical patterns with text, describing sequences and ways of transforming and combining them, exploring complex interactions between simple parts.

A network daemon that runs on the Node.js platform and listens for statistics, like counters and timers, sent over UDP or TCP and sends aggregates to one or more pluggable backend services (e.g., Graphite).

PlantUML is an open-source tool allowing users to create UML diagrams from a plain text language

Franchise is a lightweight but powerful SQL tool with a notebook interface.

Repeatable, reboot resilient windows environment installations made easy using Chocolatey packages. When its time to repave either bare metal or virtualized instances, locally or on a remote machine, Boxstarter can automate both trivial and highly complex installations. Compatible with all Windows versions from Windows 7/2008 R2 forward.

LiquidFeedback is an open-source software,
powering internet platforms for
proposition development and decision making

DemocracyOS is an online space for deliberation and voting on political proposals. The software aims to stimulate better arguments and come to better rulings.

LÖVE is a framework for making 2D games in the Lua programming language. LÖVE is totally free, and can be used in anything from friendly open-source hobby projects, to evil, closed-source commercial ones.

Open source home automation that puts local control and privacy first. Powered by a worldwide community of tinkerers and DIY enthusiasts. Perfect to run on a Raspberry Pi or a local server.

NGINX Unit is a dynamic web application server, designed to run applications in multiple languages. Unit is lightweight, polyglot, and dynamically configured via API. The design of the server allows reconfiguration of specific application parameters as needed by the engineering or operations.

Software engineering principles, from Robert C. Martin's book Clean Code, adapted for PHP. This is not a style guide. It's a guide to producing readable, reusable, and refactorable software in PHP.

Crystal is a programming language with the following goals:

Have a syntax similar to Ruby (but compatibility with it is not a goal)
Statically type-checked but without having to specify the type of variables or method arguments.
Be able to call C code by writing bindings to it in Crystal.
Have compile-time evaluation and generation of code, to avoid boilerplate code.
Compile to efficient native code.

Stencil is a compiler that generates Web Components (more specifically, Custom Elements). Stencil combines the best concepts of the most popular frameworks into a simple build-time tool.

Stencil takes features such as

Virtual DOM
Async rendering (inspired by React Fiber)
Reactive data-binding
TypeScript
JSX

and then generates standards-based Web Components with these features baked in.

tus is a resumable upload protocol, with client and server implementations for all platforms!

Feather is a collection of simple open source icons. Each icon is designed on a 24x24 grid with an emphasis on simplicity, consistency and readability.

Codemod is a tool/library to assist you with large-scale codebase refactors that can be partially automated but still require human oversight and occasional intervention. Codemod was developed at Facebook and released as open source.

Extract entities, relationships, and context from text using the Sapien Language Engine. This general natural language understanding API is used for text analytics or for building robust conversational interfaces.

flatpickr is a lightweight and powerful datetime picker.
Lean, UX-driven, and extensible, yet it doesn’t depend on any libraries. There’s minimal UI but many themes. Rich, exposed APIs and event system make it suitable for any environment.
This “lean” philosophy translates to less size and better performance, with a bonus of not having to load 8 libraries for a calendar.

Wick is a free browser-based toolkit for creating small interactive things for the Internet. With Wick, you can create games, animations, and everything in between. Your creations can run on any device with a web browser - that means mobile too. And since Wick lives in the browser, you don't have to download any extra software to use it!

Wick is a hybrid of an animation tool and a coding IDE, heavily inspired by similar tools such as Flash, HyperCard, and Scratch. It was developed in response to a growing need for such a tool for the modern web. You can read more about the creation of Wick here.