A desktop client that brings mail, calendar, contacts and tasks together, works with the main mailbox providers, and supports PGP and S/MIME encryption. A free licence covers home use. Current version 11.0.1054.

A collaboration platform that organises conversation by channel and keeps messages, files and outside applications in one interface, reachable from desktop, browser and phone, with a free tier and paid plans priced by monthly active user.

A communication tool that puts public key cryptography into everyday messaging, with chat and file sharing both encrypted end to end and an optional timer that makes sensitive messages vanish. Clients cover five systems, the code is published under a BSD licence, though the release rhythm has slowed to maintenance.

A long-established low latency voice option whose client is free and whose server can be hosted by the user. Encryption based on AES is on by default, permissions split by server or channel, and clients cover five desktop and mobile systems. The new client is still in testing.

Chat organised the way mail is organised: every message belongs to a channel and a topic, so hundreds of messages stay readable, replies can arrive days later, and self hosting is free.

Proton Mail encrypts message bodies on your device, so the provider holds ciphertext it cannot open. Swiss jurisdiction, no phone number required, a usable free tier and password protected mail for outsiders.

With commercial voice services the rooms, the permissions and the data all sit in somebody else's account. Mumble takes the self hosted route: a small server runs Murmur, and a community or a squad has its own voice house with channels, permission tiers and user management under local control.

Jami is an open source, decentralised messenger: no account to create, no central server in the path, and messages plus voice and video calls travel device to device. Free on every major platform, it hands control of a conversation back to the two people having it.

An office platform from the team behind WeChat: customers can be added as external contacts, the directory follows the real structure, documents and meetings sit in one client, and the base level is free. As of 2026-09 there are Windows and macOS desktop clients.

A team voice service that started in 2008 as a tool for group play and grew into a tree of permission-controlled channels. It still prioritises low latency and a fine-grained role system, with screen sharing and file transfer alongside the voice rooms.

A mail client that treats mail, calendar and contacts as one workspace: invitations become appointments, birthdays appear in the schedule, encryption is built in rather than bolted on, and the desktop applications are joined by an Android version.