Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
Phusion Passenger is a free web server and application server with support for Ruby, Python and Node.js.
ShareThis provides free engagement and growth tools (e.g., share buttons, follow buttons, and reaction buttons) for site owners.
WhatsApp Business is a free to download app available on Android and iPhone using which businesses can connect with their customers.