Xabber is available on the Android Play Store and another software repository that contains only apps that are what ?
F-Droid F-Droid is a software repository (or "app store") for Android applications, similar to the Google Play store. The main repository, hosted by the project, contains only apps that are free and open-source software. Applications can be browsed and installed from the F-Droid website or client app without the need to register for an account. "Anti-features" such as advertising, user tracking, or dependence on non-free software are flagged in app descriptions. The website also offers the source code of applications it hosts, as well as the software running the F-Droid server, allowing anyone to set up their own app repository.
XBEL The XML Bookmark Exchange Language (XBEL), is an open XML standard for sharing Internet URIs, also known as "bookmarks" (or "favorites" in Internet Explorer).