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.
Android Developer Lab Android Developer Lab is a series of mobile software development-focused events around the world held annually by Google. They include bootcamps and technical sessions focused on Android and give participants an excellent chance to learn about the state of the Android platform, get hands-on with the latest version of the SDK, test applications on the latest sample Android devices, get questions answered by Google engineers from the Android team as well as meet other like-minded members of the local Android developer community.