Apache is a free and open-source cross-platform web server software.
Asciidoctor is an open-source text processor and publishing toolchain, written in Ruby, for converting AsciiDoc content to HTML 5, DocBook 5, and other formats.
cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Ubuntu is a free and open-source operating system on Linux for the enterprise server, desktop, cloud, and IoT.