Ahrefs is an online toolset utilised for search engine optimisation (SEO) and competitor analysis, which permits users to analyse their website's performance, track keyword rankings, identify backlink opportunities, and research competitors' websites, among other features.
Apache is a free and open-source cross-platform web server software.
Debian is a Linux software which is a free open-source software.
Open Graph is a protocol that is used to integrate any web page into the social graph.