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.
cdnjs is a free distributed JS library delivery service.
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.
Popper is a positioning engine, its purpose is to calculate the position of an element to make it possible to position it near a given reference element.
WhatsApp Business is a free to download app available on Android and iPhone using which businesses can connect with their customers.