Repology is described as ', the packaging hub' and is an website in the OS & Utilities category. There are three alternatives to Repology, not only websites but also apps for Linux. The best alternative is pkgs.org, which is free. Other great sites and apps similar to Repology are Anitya (Free, Open Source) and whohas (Free, Open Source).
whohas is a command line tool that allows querying several package lists at once - currently supported are Arch, Debian, Fedora, Gentoo, Mandriva, openSUSE, Slackware (and linuxpackages.net), Source Mage, Ubuntu, FreeBSD, NetBSD, OpenBSD, Fink, MacPorts and Cygwin.