cdnjs is a free distributed JS library delivery service.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Java is a class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.