Social Source Commons

AdAway is an open source ad blocker for Android using the hosts file. It needs Android >= 2.1 and ROOT access.

Android is an open-source software stack for a wide range of mobile devices and a corresponding open-source project led by Google.

Any Soft Keyboard is an on screen keyboard with multiple languages support.
This is one of the most customizable keyboard available.

ChatSecure (Gibberbot) is a secure chat client capable of firewall and filter circumvention, surveillance blocking and end-to-end encryption. It works with Google, Facebook, any Jabber or XMPP server, such as OpenFire or eJabberD. Unlike Blackberry BBM’s broken single key security, Gibberbot uses the Off-the-Record encryption standard to enable true verifiable end-to-end encrypted communications.

Free unlimited, private, secure messaging with your friends over Facebook Chat, Google Talk, Hangouts, Jabber, Dukgo & more! Works with Android, iPhone, Mac, Linux or PC.

This is a free and open-source file encryption solution based on the original EncFS code. Cryptonite is fully compatible with all EncFS features. Cryptonite brings EncFS and TrueCrypt to Android. You can browse, export and open EncFS-encrypted directories and files on your Dropbox and on your phone. On rooted phones that support FUSE (e.g. CyanogenMod) you can also mount EncFS and TrueCrypt volumes.

F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.

Out of development port of FrontlineSMS for the Android platform

The GNU Privacy Guard (GnuPG) enables people to securely exchange messages and to secure files with both privacy and strong authentication. GnuPG is a free software replacement for the PGP suite of cryptographic software.

Guardian Project port to Android: https://guardianproject.info/code/gnupg/

Secure Android ROM

XDA-Developers Thread: http://forum.xda-developers.com/showthread.php?t=2317794

Guardian ROM is a custom android ROM for Galaxy Nexus and Nexus 4 devices. The ROM is completely Open Source and based off of the Android Open Source Project. The ROM aims to due the following:

Secure/Harden the android kernel with GRSecurity
Remove uneeded/Insecure binaries (Similar to SecDroid)
Replace insecure Text Messaging app with TextSecure
Include apps from the Guardian Project Installer (Optional add-on)
Include support for SQLCipher
Change Android Full Disk Encryption from AES-128 to AES-256 for more security
Allow for seperate Login and boot passwords
All of these have been completed except the final three which are underway but will take much more time.

A mobile app for controlling visual media and metadata in a manner that allows the person capturing the media to secure, protect it, and share it with only the people you intend to.

InformaCam uses the built in sensors in modern smartphones as well wi-fi, bluetooth, and cell tower information to create a snapshot of the environment in which an image or video was captured. This validates the date, time and location of capture. Digital signatures and encryption ensure that your media hasn't been tampered with and can only be opened by the intended recipient.

KeePassDroid is a port of the KeePass Password safe for the Android platform.

MultiROM is a one-of-a-kind multi-boot solution. It can boot android ROM while keeping the one in internal memory intact or boot Ubuntu without formating the whole device. MultiROM can boot either from internal memory of the device or from USB flash drive.

This is a simple open-source notepad app which demonstrates the capability of the SQLCipher for Android encrypted database library. All notes created and stored by this app are saved fully secured using industry standard 256-bit AES encryption. They are never stored in an unencrypted state on the disk, only in memory.

Open Data Kit (ODK) is a free and open-source set of tools which help organizations author, field, and manage mobile data collection solutions. ODK provides an out-of-the-box solution for users to:

1) Build a data collection form or survey (XLSForm is recommended for larger forms);
2) Collect the data on a mobile device and send it to a server; and
3) Aggregate the collected data on a server and extract it in useful formats.

Openvpn for Android is an open source client based on the open source OpenVPN project.

Based on the open-source Shadow browser from the University of Cambridge, Orweb works hand in hand with Orbot to provide web access that is able to circumvent web filters and firewalls, while also improving a users ability to remain anonymous online. Orweb also enables whitelist control of cookies, keeps no local history, disables Flash, and requires only Internet permissions, keeping you safe from malicious content. Beyond Tor, Orweb also supports any HTTP proxy server.

Ostel is a tool for having end-to-end encrypted phone calls. Our goal is to promote the use of free, open protocols, standards and software, to power end-to-end secure voice communications on mobile devices, as well as with desktop computers.

Pixelknot is an Android application that allows users to hide short text-based messages in photographs and share them across trusted channels.

RedPhone provides end-to-end encryption for your calls, securing your conversations so that nobody can listen in.

Sailfish brings and fosters innovation to offer unique differentiation and a competitive advantage for OEMs and ODMs, chipset providers, operators, application developers and retailers.

SuperSU allows for advanced management of Superuser access rights for all the apps on your device that need root. SuperSU has been built from the ground up to counter a number of problems with other Superuser access management tools.

TWRP is a custom recovery built with ease of use and customization in mind. We started from the ground up by taking AOSP recovery and loading it with the standard recovery options, then added a lot of our own features. It’s a fully touch driven user interface – no more volume rocker or power buttons to mash. The GUI is also fully XML driven and completely theme-able. You can change just about every aspect of the look and feel.

Tinfoil for Facebook is for those users that require a Tinfoil Hat when logging in to Facebook. It creates a sandbox for Facebook's mobile site in order to protect your privacy and to avoid the ability others to track your browsing history.

Twidere is a powerful twitter client for Android 1.6+ 1 , which gives you a full Holo experience and nearly full Twitter's feature.

Features
Plays all files, in all formats, like the classic VLC.
Audio and video media library, with full search.
Support for network streams, including HLS.
Supports Android from version 2.1 (platform-7).
Supports ARMv6, ARMv7 and ARMv7+NEON.
Subtitles support, embedded and external, including ASS and DVD subtitles.
Multi audio or subtitles tracks selection.
Multi-core decoding, for Cortex-A7 A9 and A15 chips.
Experimental hardware decoding.
Gestures, headphones control.

A client for WordPress blogs, which allows post creation and editing, and comment viewing, replying and moderation. Supports multiple blogs, both WordPress-hosted (wordpress.com) and self-hosted.

Module for Xposed Framework.

XPrivacy can prevent applications from leaking privacy sensitive data. XPrivacy can restrict the categories of data an application can access. This is done by feeding an application with no or fake data. There are several data categories which can be restricted, for example contacts or location. For example, if you restrict access to contacts for an application, this will result in sending an empty contact list to the application. Similarly, restricting an application's access to your location will result in a set location being sent to the application.