Open Source Software for Android
Todo.txt
With Todo.txt you can track your performance in a simple text file. Todo.txt provides a simple and intuetive text-based user interface that can be used in-application or in a command line tool of your choice. With a simple but powerful shell script called todo.sh, you can interact with todo.txt at the command line for quick and easy, Unix-y access.
Phoenix OS
Phoenix OS is an operating system specifcally designed to bring Android gaming to the PC. The OS is based on Android 7.1 and is developed and released free and open-source. With Phoenix OS you can play your Android games on a big screen, with mouse and keyboard support thanks to Octopus keymapping engine and Game Assistant, offering a powerful fundamental keymapping.
Movim
Movim is a distributed social platform, with web client and mobile apps, that protects your privacy, comes with a set of awesome features and uses the industry-standard XMPP protocol.
Nextcloud
With Nextcloud, users can host their own secure cloud solution for file storage, collaboration and communication for enterprise or personal purposes. Nextcloud gives you full control over your own data and where and how you host it. The software can be hosted on-premise or on any VPS or cloud instance provided by third-party web hosts. If you value privacy and security, Nextcloud might be the right choice for you. Nextcloud is both free and open source and developed in an open, transparent and trustworthy manner.
Jitsi
Jitsi is an open-source project and software toolset that allows you to easily build and deploy secure video conferencing solutions. At the heart of Jitsi are Jitsi Videobridge and Jitsi Meet, which let you have conferences on the internet, while other projects in the community enable other features such as audio, dial-in, recording, and simulcasting. Jitsi supports popular protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, Google Hangouts, OTR, ZRTP and more.
Firefox Focus
Firefox Focus is a free and open-source privacy-focused mobile browser from Mozilla. With Firefox Focus you can browse the web with your Android or iOS powered mobile phone in a secure and privacy focused manner. Firefox Focus allows you to easily erase your browsing history, passwords, bookmarks and cookies and prevent unwanted ads from following you across the web.
Chromium
Chromium is a free and open source web browser developed by Google. The project builds the open source version of the Google Chrome web browser. Google make use of the source code to build and improve their proprietary version of Google Chrome. And Google is not alone, many other browsers like Microsoft Edge, Opera and others a based on Chromium.
Jami
Jami is a free, open-source. universal distributed communication platform which preserves the user's privacy and freedoms. Jami supports a variety of video input options, including mutliple cameras and image and video files, and the selection of audio inputs and outputs with high quality audio and video codecs.
Matrix.org
Matrix.org is an open network for secure, decentralized communication. It gives you a simple HTTP APIs and SDKs (iOS, Android, Web) to create chatrooms, direct chats and chat bots, complete with end-to-end encryption, file transfer, synchronised conversation history, formatted messages, read receipts and more. All conversations on Matrix are replicated over all the servers participating in them, meaning there are no single point of control or failure.
Turtl
Turtl is a note taking application that uses high-end cryptography to protect your data. Whether you're worried about information leaks, competitive advantage, or blanket government surveillance, Turtl works hard to make sure only you, and those you choose, can see your data.