A single ejabberd node carries chat, device telemetry, voice calls, and federated messaging at once, because the same Erlang server speaks XMPP, MQTT, SIP, and Matrix over one authentication, storage, and clustering layer. Users get standards-based instant messaging with group chats, message archives, publish-subscribe, message carbons, push notifications, and OMEMO encryption, and your server federates with the global XMPP network out of the box. Devices publish and subscribe through the built-in MQTT broker on TCP or WebSocket transports, sharing accounts and access rules with your chat users instead of needing a second broker. Voice and video calls route through the integrated SIP gateway and STUN/TURN support, so WebRTC clients get signalling and media relay from the same deployment. Matrix support bridges federated rooms into the same infrastructure, letting two decentralised ecosystems interoperate without a separate bridge stack to babysit. Clustering with consistent hashing scales a deployment across nodes, and a single node is rated at two million concurrent sessions for very large communities. Operators manage everything from the web admin and command line, with SQL or Mnesia storage, LDAP authentication, and virtual hosting for multiple domains on one server. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-2.0 licensed.

Openfire is a self-hosted XMPP server that gives your organization its own instant messaging network, with one-to-one chat, persistent group rooms, and federation to other XMPP servers, all administered from a web console. Team members connect with any XMPP client on desktop, mobile, or the web and get presence, rosters, offline message delivery, and file sharing inside conversations. Multi-user chat rooms stay available around the clock with configurable history, moderation roles, and access controls, so a support channel or project room keeps its context instead of dissolving into scattered direct messages. The plugin catalog installs from inside the admin console and adds capabilities like message archiving and compliance monitoring, a browser-based chat client, HTTP file upload, and push notifications for mobile clients. An LDAP directory or an existing database can supply users and groups, so accounts stay in sync with the directory your organization already maintains. Server-to-server federation connects your users with contacts on other XMPP domains over encrypted connections, and load balancing spreads busy deployments across multiple instances. TLS certificates, encrypted client ports, and IP-based access lists for the admin console keep the deployment under your control from the first setup wizard onward. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

Why rent your messaging from a corporate walled garden when Tinode runs WhatsApp-style chats, groups, channels, and calls on a server you control? Teams get one-on-one and group chats that stay in sync across web, Android, and iOS, with typing indicators, delivery and read receipts, presence, replies, forwarding, editing, pinned messages, and notes to self. Communities broadcast through read-only channels with an unlimited number of subscribers, and granular permissions decide who can read, write, or invite on each topic. Support desks welcome anonymous visitors, mark staff and verified accounts with badges, and put chatbots to work with forms and templated replies. Messages take markdown-style formatting, inline images and videos, file attachments, and voice messages. One-to-one voice and video calls run peer to peer over WebRTC, using the TURN and STUN servers you configure. Administrators block unwanted contacts on the server, attach moderation plugins over gRPC, and script the rest with a command-line tool. Attachments can sit on local disk or Amazon S3, the database can be MySQL, PostgreSQL, or MongoDB, and sharded clustering with failover scales past one server. The clients offer light, dark, and system themes, custom chat wallpapers, and translations for more than a dozen languages. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.

OpenIM gives your own applications one-to-one and group chat, powered by an instant messaging server you host and client SDKs for mobile, web, and desktop. Conversations carry unread counts, drafts, pinned messages, and typing indicators, and each chat keeps paging history, keyword search, read receipts, and revoke for mistakes. Custom message payloads carry cards, orders, or any application data your product renders inside a conversation. Your backend drives the server over a REST API that provisions users, issues login tokens, creates groups with owners and members, and sends messages from trusted services. Webhooks call your business servers before and after events, so moderation, billing, and CRM workflows react as messages happen. Groups scale to hundreds of thousands of members with invitations, join requests, member muting, and group-wide mute controls. Offline messages wait on the server and sync down on reconnect, merged by message ID so nothing arrives twice. Deployment runs as Docker Compose on one host or as gateway and RPC microservices on Kubernetes. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

Benchmarked at one million concurrent WebSocket connections and 30 million delivered messages per minute on a single server, Centrifugo is a self-hosted real-time messaging server that integrates with any backend language — Node.js, Python, Go, Ruby, PHP, Java — without requiring architectural changes to your existing application. It handles persistent connections over WebSocket, HTTP-streaming, Server-Sent Events, gRPC, and experimental WebTransport, routing messages through a channel-based PUB/SUB model with automatic reconnection recovery that replays missed messages from hot channel history. Built-in horizontal scaling operates through Redis (including Redis Cluster, AWS ElastiCache, Valkey, KeyDB, and DragonflyDB), NATS, or PostgreSQL brokers, allowing multi-node deployments without external message queues. The server provides JWT-based authentication using HMAC or RSA keys, granular channel permissions, online presence tracking showing who is currently subscribed to a channel, and an RPC proxy that forwards client calls to your backend over HTTP or gRPC. The embedded ReactJS admin web interface displays real-time connection statistics, node information, and provides an interactive API console for publishing messages, managing subscriptions, and inspecting channel history. Official client SDKs are available for JavaScript, Dart, Go, Swift, and Java, with unidirectional transports requiring no SDK at all. Centrifugo also supports delta updates to minimize bandwidth, connection event proxying, and Prometheus-compatible metrics for Grafana monitoring. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache 2.0 licensed.

Your chat server should be able to talk to everyone else's chat server: Synapse is the reference homeserver for the Matrix network, hosting your users, rooms, and message history on infrastructure you control while federating openly with thousands of other servers. People keep their own identity on your domain and still message friends, colleagues, and communities elsewhere, because rooms are shared across servers instead of locked inside one company's silo. Any Matrix client works against it, from Element on phones and desktops to a shelf of community clients, and end-to-end encrypted conversations stay readable only by their participants. Bridges and application services wire the network into Slack, Discord, Telegram, IRC, and other systems, so existing conversations can move across gradually instead of in one painful migration weekend. Single sign-on through SAML or OpenID Connect folds chat accounts into the identity provider your organization already runs, and guests, registration controls, and rate limits stay in your hands. Media uploads, message history, and user data live in your PostgreSQL database and your file storage, with retention and federation policies set per room or for the whole server. When one process is no longer enough, worker processes split the load, Prometheus metrics show where it goes, and the admin API handles accounts, rooms, and moderation programmatically. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Matrix's flagship client, built by the protocol's creators: Element brings the decentralized open standard for real-time communication to web, desktop, iOS, and Android. Paired with a Matrix homeserver, it delivers Slack-quality team messaging where you own every message, file, encryption key, and byte of metadata. End-to-end encryption is on by default, built on Olm and Megolm - the Double Ratchet algorithm family Signal popularized, extended for large-room scalability and publicly audited by NCC Group. Messages encrypt per-device with cross-signed device verification, so even a compromised server yields nothing readable. Federation is the defining capability: like email, users on different homeservers converse seamlessly, and 30+ bridges connect Matrix rooms to Slack, Discord, WhatsApp, and Telegram, so moving to sovereign infrastructure doesn't sever contact with anyone. Rooms support threads, reactions, file sharing, and voice and video calls via Element Call. The result is digital sovereignty chosen by governments and enterprises across Europe: your data sits on your server in your jurisdiction, portable to any other Matrix host because the protocol is an open standard. Apache-2.0 licensed, with no per-user fees at any scale.

Blast off into productivity space with Rocket.Chat SIX, the ultimate team collaboration cosmos! Imagine a place where your messages, tasks, and projects all live in harmony, orbiting around your team's efficiency like a well-organized galaxy. This isn't just any old chat platform; it's a customizable universe where you're the master of your data domain, with the power to tweak, integrate, and innovate to your heart's content. Ready to provide stellar customer service? Engage with your clients in a way that's so contextually on-point, they'll feel like you're mind-reading across the cosmos. Plus, with a chat engine that's like a gravitational pull for user engagement, your app or website will become the center of your users' universe. And for the security-conscious space cadets, fear not! Rocket.Chat SIX is locked down tighter than a spaceship hatch, with end-to-end encryption and a buffet of deployment options to satisfy your security appetite. All this, hosted on RepoCloud, where the cost is as lightweight as zero-gravity. So why settle for a terrestrial tool when you can have a celestial experience? Rocket.Chat SIX: because your team deserves to collaborate in a universe that's light-years ahead!

Teams that cannot send messages through someone else's cloud run Mattermost - the open-core, self-hosted alternative to Slack. It provides public and private channels, threaded discussions, unlimited search history, file sharing with previews, one-to-one audio calls, and screen sharing, with desktop clients for Windows, macOS, and Linux plus iOS and Android apps. Messages support full Markdown, which suits engineering conversations with code blocks and logs. Playbooks turn repeatable processes such as incident response and release management into checklist-driven workflows with automated triggers and retrospectives. Integration is a core strength: prebuilt connectors for GitHub, GitLab, Jira, ServiceNow, and PagerDuty, plus webhooks, slash commands, bots, a REST API, and a plugin marketplace with 700+ entries - together making it a working surface for ChatOps rather than just a chat room. Playbooks add keyword and event triggers, task assignment, status broadcasting, and post-incident retrospectives, so operational knowledge is not trapped in individuals' heads. The server is a single Go binary backed by PostgreSQL, with React clients, released monthly under MIT license and deployable fully air-gapped - which is why governments and defense organizations run it inside closed networks, and why the same control applies to any team with confidentiality requirements. The compiled Team Edition is free for unlimited users with no message history cutoff, so costs stay flat as the team grows.

Used by the Rust language community, NASA, Dropbox, and thousands of organizations worldwide with over 25,600 GitHub stars and 1,500+ contributors, Zulip is the only modern team chat app designed from the ground up for both real-time and asynchronous communication through its unique topic-based threading model where every message belongs to a named topic within a channel. This eliminates the context collapse of linear chat by letting teams follow specific conversations without scrolling through unrelated messages, resume threads days later without losing context, and catch up on missed discussions at per-topic granularity. Server 12.0 introduced end-to-end encryption for mobile push notifications, AI-powered search ranking, channel folders for workspace organization, and expanded video conferencing with Jitsi, BigBlueButton, and Zoom integration. Over 100 native integrations connect GitHub, GitLab, Jira, Sentry, PagerDuty, Travis CI, Redmine, dbt, Nextcloud, and n8n with bidirectional notifications, while LLM-driven agents access web-public channels via a standard llms.txt interface. Full-text search covers unlimited message history across all plans, code blocks render with syntax highlighting for 250+ languages, and LaTeX math expressions display inline. The REST API with typed Python and JavaScript SDKs enables custom bots, webhook integrations, and programmatic administration. Import tools migrate entire workspaces from Slack, Microsoft Teams, Mattermost, and Rocket.Chat. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache 2.0 licensed.

Stoat delivers a complete Discord-like community chat experience that organizations can self-host on their own infrastructure with full data ownership. The platform provides text channels organized in categories, real-time voice calls powered by LiveKit, file sharing with automatic media proxying, custom emoji support, bot framework, GIF search, server invites, and granular role-based permissions — all wrapped in a polished web UI that feels immediately familiar to Discord users. The architecture separates concerns across dedicated Rust binaries handling the REST API, WebSocket real-time events, file storage with S3-compatible backends, push notifications, and media proxying, backed by MongoDB for persistence and Redis for caching. Web, desktop, and mobile clients connect through the same API, ensuring consistent experience across platforms. Unlike federated alternatives such as Matrix, Stoat provides a single-server deployment model focused on the Discord-style community experience: server invites, channel categories, member management, and an invite-first onboarding flow that communities expect. The Docker Compose deployment stack handles all microservices with Caddy providing automatic TLS via Let's Encrypt. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

IRC never died, it just waited for a server that behaves like people chat now: Ergo runs your own IRC network where nobody loses the thread when a laptop closes. The server remembers channel and direct message history and replays what you missed when you reconnect, and your nickname stays present around the clock like a bouncer, so conversations keep their context. Connect your phone, desktop, and terminal clients to the same nickname at once and each one stays in sync. NickServ accounts, ChanServ channel registration, and HostServ vanity hosts are built in rather than bolted on, and SASL, client certificates, and bcrypt hashed passwords keep sign-in sane. Modern IRCv3 capabilities power typing notifications, message replies, and rich history requests for clients that support them, and UTF-8 nicknames and channel names work when you want them. Operators get a unified ban system, connection limits, IP cloaking, LDAP integration, and a YAML configuration that reloads live with a rehash, certificates included. One small binary or container is the whole network, equally at home for a friend group, an open source project, or a company that still loves plain text chat. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Your IRC networks and channels stay alive on the server around the clock under ZNC, which replays everything you missed the moment your client reconnects. Connect from your desktop, laptop, and phone at the same time, all sharing one identity and one scrollback. Each channel keeps a configurable playback buffer, so a client that reconnects after hours offline receives the conversation it missed instead of a blank window. Detach from a channel without leaving it: ZNC keeps your nick present, answers pings, and holds your place while no client is attached. Separate users on one instance each get their own networks, channels, and settings, which makes a single server a shared bouncer for a whole team or community. The web administration panel creates and edits users, networks, and global settings from a browser. The control panel module exposes the same controls through IRC commands. Modules extend the core in C++, Python, or Perl, adding everything from SASL authentication and away handling to message logging and push notifications. SSL/TLS encryption protects both the IRC connections and the web panel, with IPv6 supported alongside IPv4 on every listener. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

Families and small communities run their own messenger with Databag, where accounts live on a little home server and chats never pass through a platform company. Conversations live in topics instead of contact threads, so the ski trip, the shopping list, and the school parents each keep their own stream with unlimited participants. Seal a topic and end-to-end encryption means even you, the admin, cannot read it on the server. Friends on other Databag nodes join the same topics because accounts federate across servers, and identity comes from a public-private key pair rather than a phone number or a rented domain. Photos, videos, and files ride along in the thread, audio and video calls connect from the mobile and browser apps, and push alerts arrive through UnifiedPush, FCM, or APN when something new lands. The whole node sips resources, happily running on a Raspberry Pi class machine, and websockets deliver messages with low latency instead of polling. Host unlimited accounts for the whole household, protect sign-in with TOTP multi-factor authentication, and manage everything from apps on iOS, Android, F-Droid, or any browser. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

MiroTalk P2P gives your team browser meeting rooms with video, screen sharing, and chat, where the media travels directly between participants instead of through a rented cloud. Create a room, send the link, and guests join from any modern browser with nothing to install and no account to create. Calls carry video at high frame rates, and anyone can share a full screen, one window, or a browser tab to walk through documents and slides. The built-in recording captures screen, camera, and audio in the browser, ready to download and pass along after the meeting. Chat supports Markdown formatting and emoji, and the room also packs a collaborative whiteboard, a shared text editor, live polls, and breakout rooms. Files move between participants inside the call, and speech recognition plus voice commands keep hands free during long sessions. Hosts lock rooms with passwords, hold arrivals in a lobby, and require approval before strangers wander in. Sign-in through OIDC, per-room JWT credentials, and host protection controls keep recurring meetings behind your own identity provider. A full REST API creates rooms from your own tools, Slack and Mattermost commands start calls from chat, and an iframe embed drops meetings into existing pages. The interface speaks 133 languages, and an optional ChatGPT assistant joins rooms to answer questions in the conversation. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

With over 20,000 GitHub stars and adoption by companies building everything from telehealth platforms to AI voice agents, LiveKit is the most widely deployed open-source real-time communication server available. The Go-based Selective Forwarding Unit handles hundreds of concurrent participants per node with adaptive bitrate streaming, simulcast layers, SVC codec support for VP9 and AV1, and end-to-end encryption. Client SDKs span JavaScript, Swift, Kotlin, Flutter, React Native, Rust, Python, Unity, and ESP32 embedded devices, while server-side APIs cover Node.js, Go, Ruby, Java, Python, Rust, PHP, and .NET. The Agents framework enables building AI-powered voice and video applications — real-time speech-to-text, LLM-driven conversations, and computer vision pipelines — running as server-side participants in any room. Egress records sessions to S3-compatible storage or streams to RTMP endpoints, while Ingress pulls external feeds from OBS via RTMP, WHIP, or SRT into LiveKit rooms. The SIP bridge connects traditional telephony to WebRTC rooms for hybrid conferencing. JWT-based authentication, webhook notifications, room-level moderation APIs, and selective subscription give operators granular control. Deploy as a single binary for development, Docker Compose for production single-node, or Kubernetes with the official Helm chart for distributed multi-region clusters using Redis for state coordination. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache 2.0 licensed.