Termux is an Android terminal emulator and Linux environment app that works directly with no rooting or setup required. A minimal base system is installed automatically - additional packages are available using the APT package manager. Termux combines standard packages with accurate terminal emulation in a beautiful open-source solution. Access API endpoints with curl and use rsync to store backups of your contact list on a remote server.
The OwnTracks Recorder is a lightweight program for storing and accessing location data published via MQTT (or HTTP) by the OwnTracks apps. It is a compiled program which is easy to install and operate even on low-end hardware, and it doesn't require an external database. There are two main components: the Recorder obtains data via MQTT subscribes or HTTP POST, stores the data in plain files and serve it via its built-in REST API, and the ocat command-line utility reads stored data in a...
Microsoft project for cloud-based client-server communication
...HTTP client/server, JSON, URI, asynchronous streams, WebSockets client, oAuth. A powerful model for composing asynchronous operations based on C++ 11 features. Windows desktop, Windows Store (UWP), Linux, OS X, Unix, iOS, and Android. Support for Visual Studio 2015 and 2017 with debugger visualizers.