In addition to the systems listed in system comparison, there are many other interesting projects, a few of which are listed here. Even though little information has been collected on some of these, they should not be neglected.
In the following overview, a German website is rated as positive and a lack of German-language information as negative. Why? It would be arrogant to assume that “everyone” understands English or even to demand basic knowledge. Information should be understood by every native speaker and unnecessary misunderstandings due to insufficient translations should be avoided. Good translations make a product in general (here: Messenger) interesting and accessible to the masses, because you save many interested people/users unnecessary translation effort. They are enormously helpful and therefore worth their weight in gold.
Also “serverless” are LAN messenger, but they cover a completely different use case.
Regardless of the solution used, the app “Oversec” can also be used on Android devices. This app virtually overlays others and encrypts/decrypts inputs before they are in the actual messenger. Sounds crazy, but it’s not and works great. So security-minded people should definitely take a look at this app!
Download: at F-Droid (external) or directly as APK: https://www.oversec.io/#download (external)
Project page: https://www.oversec.io (external)
Note: Oversec is probably not actively developed anymore since 2019 / it does not respond to Github-issues anymore.
Source code: https://git.anonymousmessenger.ly/dx/AnonymousMessenger (external)
Project page: https://anonymousmessenger.ly (external)
Sends to ALL participants, only the recipient can decrypt and read message (no sender/recipient address).
More information: >> here <<
Databag is a self-hosted messenger (and should actually be listed under server-based messenger systems).
With its extensive range of functions and focus on data protection and security, the aim is to offer a comprehensive and reliable self-hosted messaging solution. Databag’s ultimate goal is to also be embedded/used in low-cost electronics to reach a much broader, less technical audience. Currently, the network node runs well on a Raspberry Pi Zero v1.3. as extremely few resources are required. Key features include:
The messenger can even be tested in a test instance (external). But please do not post anything important, as the server is deleted regularly.
Information directly from the developer:
Coupled with the resource requirements is efficiency and fast client synchronization. The user does not have to wait for the client to pick up all conversations when the app is first started or when it is restarted after a long period of time. The data model for Databag is very simple and you know where your data is. The data is only located on the node of the account for the conversation and the designated client devices.
The Databag node (protocol/API) is abstract and does not focus primarily on message exchange, but simply on data sharing. The Databag network is open, and I have several other applications I want to write for the network (notably decentralized ratings and file sharing by trusted contacts).
Technical details: End-to-end encryption is implemented with RSA and AES. The synchronization data is transmitted as a body of HTTP messages.
Name development: “SFLphone” -> “Ring” -> “Jami”.
Originally developed for telephony (audio / audio and video / audio and video in groups, depending on the operating system), but text messaging is also possible; text-based chat rooms are being worked on.
Jami enables secure text, voice and video communication over the Internet. It also allows teleconferencing and videoconferencing, but strangely no text-based chatrooms yet, as the developers are trying to make these fully decentralized. Jami is a good choice for secure phone calls over the Internet, as long as the people on the call are also using Jami. Jami is a peer-to-peer system; it does not rely on or require central servers.
Jami is cross-platform, with versions for Android, FreeBSD, iOS, iPhone, Linux, Microsoft Windows, and OS X. There is (as of March 2020) no version for the Pinephone.
It is both a peer-to-peer voice-over-IP client program and a custom protocol for service discovery using a distributed hash table (DHT). It uses SRTP to transfer communication data.
P2P with server?
We keep saying that Jami’s most distinctive and innovative characteristic is the fact that it doesn’t require a server to relay data between users. There are many advantages associated with that, including increased privacy, light infrastructure, high scalability, no bandwidth restriction (other than that of your Internet connection), no size limit for file transfers, and more. This is all true, but while servers are not required, they are still used in five specific cases: push notifications, the OpenDHT proxy, bootstrap, name server, and TURN. … >> more << (external)
Description: https://linuxreviews.org/Jami (external; English)
Security questions and answers from a developer: stackexchange.com (external)
Using GIT for messages (‘swarm’): jami.net (external; english)
Also available via F-Droid and thus without tracker: https://f-droid.org/en/packages/cx.ring (external)
Traffic analysis resistant messaging - We write mix network protocol libraries. What is a mix network? It is an anonymous communications system… however the word anonymous is problematic because some government authorities equate anonymity with terrorism. We prefer to instead call it “network security” because you can feel more secure when you communicate using traffic analysis resistant communications protocols. …
This project has received funding from the “European Union’s Horizon 2020 research” and innovation programme”, the “Samsung Next Stack Zero grant” and “NLnet and the NGI0 PET Fund paid for by the European Commission”.
Source and project page: https://github.com/neuravion/mesh-chat-protocol (external; englisch)
A messaging platform that uses Tor and IPFS and sees itself as an alternative to Slack and Discord.
Each group, referred to as a “community” in Quiet, works in its own network. This guarantees that the data of a community remains completely isolated from the devices of other Quiet users, even if it is encrypted.
The synchronization of messages is seamlessly facilitated by OrbitDB, which combines the features of Git, a Gossip protocol, and BitTorrent. It efficiently sends new messages, synchronizes recent messages and retrieves files. As a result, users can expect to receive all messages that were sent while they were offline.
Invitations, access permissions and usernames are assigned exclusively by the owner of the community, who takes responsibility for creating the community.
The owner provides an exclusive “invite code” that allows invitees to connect to their device, register a username and purchase a standard cryptographic certificate to confirm their membership to other peers within the community.
This is how Quiet sees itself compared to Slack, Discord, Signal, Matrix, Session, Briar, Cwtch, Cabal and Ricochet Refresh: https://medevel.com/quiet (external)
Ricochet Refresh is a maintained and up-to-date fork of the former Ricochet project.
Source code: https://github.com/blueprint-freespeech/ricochet-refresh (external)
Project page: https://www.ricochetrefresh.net (external)
Federated via TC providers and works on the basis of SMS.
If you think you are really being targeted by secret services, you should take a look at the hardware-supported chat solution TinfoilChat (TFC). They seem to be serious and this is one step more “extreme” than e.g. Briar:
Tinfoil Chat (TFC) is a FOSS+FHD peer-to-peer messaging system based on a highly secure hardware architecture to protect users from passive collection, MITM attacks, and most importantly remote key exfiltration. TFC is designed for people with one of the most complex threat models: organized criminal groups and government hackers who bypass the end-to-end encryption of traditional secure messaging apps by hacking the endpoint.
Source and project page: https://github.com/maqp/tfc/ (external; unfortunately only english; really exciting to read!)
Audio and video calls are possible and there are different clients with graphical as well as text-only user interface.
Field report: https://herrdoering.de/de/sicheres-messenging-mit-tox-chat/ (external)
Usage with TOR: https://wiki.tox.chat/users/tox_over_tor_tot (external)
Raspberry Pi for offline messages (external; english)
Possible clients: qTox, uTox, Toxygen, Toxic, aTox (external), Trifa (external)
Client functions: https://wiki.tox.chat/clients#features (external)
Source and project page: https://tox.chat (external)
Also an interesting project - but currently no active further development anymore (last change to the source code was in September 2019).