Chat "off-the-grid" with people around you – even if there is no Internet connection or mobile phone coverage.

Hubzilla is a powerful platform for creating interconnected based websites featuring a decentralised identity, communications, and permissions framework built using common webserver technology. Hubzilla is very suitable for communities (of any size).

Threema is a new mobile messaging app that puts security first. With true end-to-end encryption, you can rest assured that only you and the intended recipient can read your messages.

iptablesbuild is effectively a configuration manager for iptables. It is intended to manage iptables configurations in a centralized location for multiple systems.

AOKP stands for Android Open Kang Project. It is a custom ROM distribution for many Android devices. It is mostly based off of AOSP.

MiniKeePass provides secure password storage on your phone that's compatible with KeePass.

dnscrypt-proxy - A tool for securing communications between a client and a DNS resolver

Secure and encrypt entire partitions or devices, including system drives, with automated, real-time protection and enhanced security measures.

Secure Swiss-based email with end-to-end encryption and zero third-party access. Available across devices, offering a free version to promote privacy.

LUKS is the standard for Linux hard disk encryption. By providing a standard on-disk-format, it does not only facilitate compatibility among distributions, but also provides secure management of multiple user passwords.

Surf the web through the Tor network with this open source browser for iOS devices.

An example application that demonstrates how to build peer-to-peer Web applications with Beaker Browser, Dat, and WebDB.

Friendica is a distributed social network application. Which allow users to connect with others via their own Friendica server, but may also fully integrate contacts from other platforms including Twitter, diaspora*, Pump.io and StatusNet into their 'newsfeed'.

OpenWrt Project is a Linux operating system targeting embedded devices. Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the...

Cisco Umbrella (formerly OpenDNS) provides the first line of defense against threats on the internet wherever users go.

CryptoKitties is a game centered around breedable, collectible, and oh-so-adorable creatures we call CryptoKitties! Each cat is one-of-a-kind and 100% owned by you; it cannot be replicated, taken away, or destroyed.

Gufw is an easy, intuitive way to manage your Linux firewall. It supports common tasks such as allowing or blocking pre-configured, common p2p, or individual ports port(s), and many others! Gufw is powered by Uncomplicated Firewall (ufw).

Ethereum is a decentralized platform that runs smart contracts: applications that run exactly as programmed without any possibility of downtime, censorship, fraud or third party interference.

Cock.li is your go-to solution for professional E-mail addresses and XMPP addresses. Since 2013 cock.li has provided stable E-mail services to an ever-increasing number of users. Cock.li allows registration and usage using Tor and other privacy services (proxies, VPNs) and is...

Windscribe VPN is your all-in-one solution for privacy, security, and unrestricted internet access.

Federated and open-source social network with no ads, 500-character limit, custom emojis, and content warnings, emphasizing privacy and personal interaction.

Open-source password manager storing passwords, notes, and attachments offline with AES-256 encryption, browser extensions, cross-platform support, and TOTP.

CryFS encrypts your files, so you can safely store them anywhere. It works well together with cloud services like Dropbox, iCloud, OneDrive and others.

Mesh routing protocol designed to handle a massive amount of nodes with very low resource consumption. Thanks to this feature it can be easily used to build a worldwide distributed, anonymous and uncontrolled network, separated from the Internet, without the support of any...

A security and privacy focused mobile operating system compatible with Android apps. Google-free secure Android for the latest hardware.

Free and open-source Android-based OS for smartphones and tablets that enables deep customization, regular security updates, privacy focus, and broad device compatibility.

A decentralized messaging and sharing app built on top of Secure Scuttlebutt (SSB).

Zcash is the first open, permissionless cryptocurrency that can fully protect the privacy of transactions using zero-knowledge cryptography.

[TrueCrypt is not exactly "Open Source", but the source is available. See the reviews to get more information.]