Open-source Signal alternatives

SimpleX is a messaging network built around the idea that it should not assign identifiers of any kind to its users, not even random IDs, which the project says makes it private by design. The goal is to protect not just message content but also metadata, meaning who talks to whom and when.

Messages use double-ratchet end-to-end encryption with an additional encryption layer. Apps are available for Android and iOS, with an iOS TestFlight preview that gets new features a week or two earlier but is limited in the number of users, and a terminal client runs on Linux, macOS and Windows. The README invites readers to install the app, connect to the team and user groups, make a private connection with a friend, help with translations and donate. The core is written in Haskell.

SimpleX Chat is licensed under AGPL-3.0, and its protocol and server software are open so that others can host relays. It is aimed at people who need stronger privacy guarantees than mainstream messengers provide, such as journalists, activists and privacy-conscious individuals.

Element Web is a client for Matrix, the open protocol for decentralized messaging. It is the web and desktop application formerly known as Vector and Riot, and it lets people join rooms, chat in teams and communities, and collaborate across Matrix servers rather than inside a single vendor's network.

The client is built with TypeScript on top of the Matrix JS SDK. The README defines support tiers for browsers, covering recent versions of Chrome, Firefox, Edge and Safari on desktop, best-effort handling for ESR and extended-stable releases, and community support for mobile web. For phones and tablets the maintainers recommend the native Element X apps for Android and iOS.

It is released under the AGPL-3.0 license and is typically served from your own web host or used through the hosted app from the vendor, Element. Related products such as Element Call and the Enterprise Server Suite are mentioned as part of the wider Element offering. Changes are tracked on GitHub with regular release cycles.

Element Android, also called Element Classic, is a previous-generation Matrix collaboration client for Android provided by Element. It runs on Android devices with Lollipop (API 21) or newer. The README says this client is still supported and receives security updates, but no new features or usability improvements are being made, and it recommends the next-generation Element X app instead. The code is written in Kotlin and licensed under AGPL-3.0.

The project is built on a new Android SDK written entirely in Kotlin, which shares the repository with the app during early development. At each release the SDK module is copied to the matrix-android-sdk2 repository so that third-party apps can use it as a regular Gradle dependency. The README also explains the delay between a GitHub release and its appearance on Google Play and F-Droid, which includes beta periods and store reviews.

FluffyChat is a nonprofit, open-source client for the Matrix network, written in Flutter. Its goal is to be an easy-to-use instant messenger that is open source and accessible to everyone. Because it speaks the Matrix protocol, it works with Matrix accounts and servers rather than a proprietary service of its own.

Users can send all kinds of messages, images and files, record voice messages, share locations and take part in video calls with Matrix RTC. It supports push notifications, unlimited private and public group chats, public channels, spaces, custom emotes and stickers, and moderation tools covering the Matrix feature set. Privacy features include end-to-end encryption, encrypted chat backup, emoji verification and cross-signing, and it follows Material You design.

For organizations, configuration can be pushed to Android and iOS devices through mobile device management since version 2.10.0, and on the web through a config.json file. Building from source requires Flutter and Rust. It is licensed under AGPL-3.0, with translations handled through Weblate and installation instructions on the project website.

Delta Chat Desktop is the desktop application for Delta Chat, described as a decentralized private messenger with chat-shared tools and games. Project topics show that it works over standard email protocols, IMAP and SMTP, and supports Autocrypt-based end-to-end encryption, so conversations can run over existing email accounts instead of a single central service.

The default edition is built on Electron and is the version deployed in app stores and used by most people. A highly experimental browser edition with a web server component is meant only for developers and automated testing, and a work-in-progress edition based on Tauri lives in a separate repository. The code is written in TypeScript and licensed under GPL-3.0.

Binary releases are published for supported platforms, with Flatpak and Arch Linux options on Linux, Homebrew or a DMG on macOS and installers for Windows. User documentation covers troubleshooting, command-line flags, keybindings and creating custom themes, while developer documentation explains logging, styling, updating the core, end-to-end tests and the release process.

Session Desktop is the desktop application for Session, a private messenger that is decentralized and uses onion routing. It connects to Oxen Service Nodes, a set of distributed, Sybil-resistant servers. Some of these nodes store messages while a recipient is offline, and others provide onion routing that hides users' IP addresses.

Releases are signed, and the README walks through verifying them by checking a GPG signature on the published hashes and then comparing the hash of the downloaded file. The project also lists supported platforms and system requirements, accepts pull requests on a development branch, and invites volunteers to help with translations. Build instructions are in the contributing guide.

The client is written in TypeScript and licensed under GPL-3.0. It is distributed from getsession.org and maintained under the Session Foundation. The README points to the Session whitepaper for a full explanation of how the system works.

ChatSecure is a messaging client for iOS that uses the open XMPP protocol and focuses on encrypted communication. It is aimed at privacy-conscious users and developers who want a free, inspectable alternative to closed messaging apps, with the ability to connect to any XMPP-compatible chat service rather than a single vendor's network.

It integrates OTR and OMEMO encrypted messaging, the same protocols used by other secure clients such as Conversations on Android and Dino on desktop, and offers optional integrated support for routing connections over the Tor network for additional anonymity. The app is free to download, since the project considers privacy tools something everyone should be able to access regardless of ability to pay, and development is supported through GitHub Sponsors and PayPal donations.

The README notes that although the code is open source, redistributing it in closed-source commercial products on the App Store requires contacting the maintainers first, with an exception process for other open-source projects. ChatSecure is written in Objective-C and Swift, built with CocoaPods, and released under a license listed as Other, so check the license file before reuse.