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.

On game night Sharkord carries voice, webcams, and screen sharing, and on Monday morning it carries the team's threaded chat, all from one server you control. For the gaming crowd, voice rooms offer noise suppression, echo cancellation, webcams up to 2160p, and screen sharing in VP8, VP9, H264, or AV1, with optional simulcast layers for slow viewers. An experimental Bridge app keeps push-to-talk and mute hotkeys working with a game in focus, and plugins add a music bot or a soundboard. For a family group, invite links can carry a role, a use limit, and an expiry, and replies, reactions, custom emoji, pins, and direct messages keep conversation casual, with uploads up to 2 GB each. For a small team, text channels sit in categories with threads, mentions, and search, roles stack with per-channel permissions for private rooms, and OpenID Connect sign-in works with Authentik, Keycloak, Zitadel, Entra ID, or Google Workspace. Admins cap storage per user or role and can sign upload URLs. There is no premium tier, no member cap, no ads, and no tracking, and a built-in marketplace installs plugins in one click. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

No per-seat fees, no landlord, no shutdown notice: phpBB gives your community the complete bulletin board package on a server you own. Organize discussion into categories holding unlimited forums and subforums, each with its own rules, password, style, or redirect, and let members post in flat topics with quoting, BBCode formatting, file attachments, polls, smilies, and emoji. Members register through configurable anti-spam checks, subscribe to forums and topics, keep bookmarks, exchange private messages with folders and drafts, and get notified about replies and mentions in their notification center. Moderators work from their own control panel with approval queues, reported-post handling, warnings, topic tools, pruning, and bans by username, email, or IP range, while the famous permission system assigns forum, moderator, and admin roles per user or group and can trace exactly why any member can or cannot do something. Administrators run everything from the ACP: styles built on the responsive prosilver theme, extensions installed from the validated catalog, language packs for a global audience, search and cache backends, scheduled tasks, and database backups. Whether it is a support board, a hobbyist community, or a company knowledge commons, the conversation stays on infrastructure you own. 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.

Think of it as a team messaging platform where every feature beyond core chat is a plugin you can install or remove, inspired by VS Code's extension model but applied to real-time communication. The Moleculer microservice backend scales horizontally across nodes while Socket.io delivers instant message synchronization with text, images, files, mentions, reactions, and rich Markdown formatting. Available plugins provide LiveKit video conferencing, collaborative drawing boards, task management panels, end-to-end encryption, custom themes, and third-party push notification reception without touching core code. Groups use a two-level space system with customizable panel layouts arranged through drag-and-drop, while role-based access control enforces fine-grained permissions across the organization. The Open Platform exposes OAuth for single sign-on across connected applications and a Bot API enabling bidirectional message processing between Tailchat and external services via HTTP requests. Multi-platform clients cover web, Electron desktop with screenshot capabilities, and mobile apps with native push. Docker Compose deployment bundles MongoDB for persistence, Redis for caching and transport, and MinIO for S3-compatible file storage. Deploy on RepoCloud with a dedicated VPS for persistent team infrastructure under the Apache 2.0 license.

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.

With over 7,500 GitHub stars and 140 contributors, Matterbridge is the Go-powered chat bridge that connects over 20 messaging platforms through a single TOML configuration file, letting teams communicate across platform boundaries without forcing anyone to switch applications. The gateway architecture routes messages bidirectionally between any combination of Discord, Slack, Telegram, Matrix, IRC, Mattermost, Microsoft Teams, XMPP, Rocket.Chat, Nextcloud Talk, Keybase, Mumble, Twitch, WhatsApp, VK, Gitter, Zulip, ssh-chat, and Harmony, with transparent username and avatar spoofing so bridged messages appear native on each platform. Message edits and deletes propagate across bridges, file attachments and inline images transfer between protocols, threading and reply context is preserved where platforms support it, and private group bridging enables confidential cross-platform conversations. Multiple independent gateways can run simultaneously, each bridging different channel sets with different protocol combinations. The REST API enables third-party integrations and custom bridges without modifying the Matterbridge codebase, while the tengo scripting engine allows inline message transformation and filtering. Game chat support bridges Minecraft and Counter-Strike server chat into messaging platforms. Deployment runs as a single static Go binary with zero dependencies, or as the official Docker image with the configuration file mounted as a volume. 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.

Chitchatter is a browser-based chat room for text, voice, video, screen sharing, and file transfers that exists only while its members are connected and keeps no record of what was said. Every visit starts with a random room name generated on your device, a UUID or a readable passphrase, and you invite people with the link or a QR code. Public rooms admit anyone with the link; private rooms also require a matching password. Messages support Markdown, multiline text, and code blocks, and clicking a name opens a direct conversation. Newcomers to public rooms receive the earlier conversation from peers already there, and typing indicators show who is writing. Start an audio or video call, share your screen to walk a relative through a settings problem, or hand over a file of any size, encrypted before it leaves your browser. Public-key checks verify each peer automatically, with a green lock marking everyone who passes and an icon showing whether the link is direct or relayed. Embed a room in any web page with an iframe or a web component that takes a room name, user name, and color mode. Light and dark themes are built in, and notifications and sounds announce new messages while you work in another tab. Close the tab and the transcript disappears. 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.

Polaris puts app deploys, file storage, team chat, tasks, and a password vault behind one login on a server you control. Deploy from a Git repository or an image with databases, volumes, environment variables, logs, a terminal, and a domain, published through your own domain, a Cloudflare tunnel, or DuckDNS. Enroll more machines over SSH with one generated command, then watch their containers and metrics and schedule backups with restore. Drive spans local disks, SFTP, S3-compatible storage, SMB, NFS, Google Drive, OneDrive, and Dropbox, with password-protected public links, expiry, and drop points for people without an account. Vault works with the Bitwarden apps and extensions and encrypts in the browser, so the server never sees your master password. Chat brings channels, threads, direct messages, voice and video calls, screen sharing, and a soundboard, while Tasks adds lists, boards, sprints, goals, and time tracking, and can hand work to coding agents over MCP. Calendar syncs both ways with Google, Microsoft 365, and CalDAV and offers booking pages. Game servers run Minecraft, ARK, and FiveM, a firewall blocks countries, networks, and bots, and one-click Marketplace installs add more apps. The interface comes in English and Spanish. 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.

Nodyx puts forum threads, real-time chat channels, peer-to-peer voice calls, collaborative whiteboards, and a drag-and-drop homepage builder behind one installation script on hardware you control. Create categories and threaded discussions that search engines index, then switch to Socket.IO-powered chat rooms where replies, pins, link previews, and @mentions update instantly. Voice channels connect participants through WebRTC mesh networking, keeping audio between peers without routing through third-party servers; a Rust-based STUN/TURN relay handles restrictive NATs so home-server deployments work without port forwarding. The NodyxCanvas layer adds CRDT-synchronized collaborative drawing with 11 tools, voice-aware cursors, and board-scoped chat, all persisted to PostgreSQL snapshots. Build your community's landing page with a visual editor that places widgets across 11 layout zones, then extend functionality by dropping third-party widget archives into the admin panel or authoring your own with the plain-JavaScript Widget SDK. Private conversations stay end-to-end encrypted with ECDH P-256 key exchange and AES-256-GCM ciphers where the private key never leaves the browser, and the OctoGuard module automates moderation with five matcher types plus configurable actions from muting to banning. For streamers, a native Streamer Hub bridges Twitch chat bidirectionally, provides a drag-and-drop soundboard, generates OBS browser-source overlays, and offers a mobile Stream Deck. Instances discover each other through a gossip protocol, forming a decentralized network without central coordination. 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.

Fluxer gives friends, gaming groups, and private communities their own self-hosted instant messaging and VoIP platform that replaces Discord with private text channels, voice rooms, video calls, and screen sharing. Members can chat one-on-one in direct messages, form multi-person group conversations, or organize large community servers into categorized text and voice channels with threaded replies, reactions, and typing indicators. When a conversation moves to voice, participants can join low-latency audio and video rooms from multiple devices simultaneously, share application windows or full screens, and rely on built-in noise suppression and echo cancellation for clear calls. Rich media support allows users to share file attachments, preview embedded links, search animated GIFs through KLIPY, and upload custom community emojis and stickers. Server administrators control access through role-based permission hierarchies, member timeouts, kicks, bans, and detailed moderation audit logs that track every configuration change across the community. Integrated full-text search lets members quickly locate historical messages, code snippets, and shared files across every channel they can access. 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.

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.

"Forget about bouncers" became a real sentence because of The Lounge: a Node.js web IRC client that holds persistent connections to your networks 24/7, logging everything while you sleep, so closing the browser tab never means missing a message or losing your place in a channel. Open it again from any device - desktop, phone, tablet - and you resume exactly where you left off, with full history synchronized. Because it combines bouncer and client in one process, the experience feels like a modern chat app rather than 1990s infrastructure: push notifications for highlights and private messages (with self-generated VAPID keys, so even Web Push needs no third-party service), automatic link previews, inline file and image uploads, and full IRCv3 protocol support. It installs as a progressive web app from any modern browser, so phones get a native-feel client without an app store. Multi-user support means one instance serves your whole team or community, each user with their own networks and history, and LDAP integration ties into existing authentication. A public mode alternatively serves as an open, registration-free web chat for events or support channels. MIT-licensed, born as a fork of Shout, and a fixture of self-hosting stacks since.

Share a game, a film, or your holiday photos with up to 20 friends, and let them watch from a browser tab with nothing to install. The host picks a screen, window, browser tab, or camera, then sends an invite link or a four-digit room code, with an optional room password. Friends open it on a desktop or phone, press Play, and chat or react while it runs, with optional on-screen chat. A microphone switch adds spoken commentary, with a choice of input device and voice volume. Video travels directly between participants where possible, and a self-hosted server can add automatic forwarding for networks that block direct links. Sharing settings cap resolution from 480p to 1440p, frame rate up to 60 fps, and audio at 64, 128, or 192 kbps, with Clarity, Balanced, and Fluency presets and a choice of VP8, H264, or automatic codecs. Viewers get playback controls, picture-in-picture, fullscreen, light and dark themes, and a connection topology view. The interface follows the system language in Chinese or English, with a visual-only mode for a text-free look. Piik App adds native capture on Windows, macOS, and Linux, while a hosted site works from any desktop browser. A self-hosted site can set a site passphrase, a viewer limit per room, and automatic cleanup of empty rooms. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Think of Storyden as running your own small Reddit, except the knowledge your community produces does not scroll away and die in the feed. Discussion happens in threaded forums organized by categories and tags, where posts collect replies, likes, emoji reactions, and saves into personal collections. Beside the chatter sits the Library, a tree of rich pages your members build together into wikis, directories, catalogs, and guides that stay findable. Library pages carry typed properties, attached files, and table views, so a car club can track vehicles as data instead of arguing over a spreadsheet. Threads can reference Library pages and pages can link back to threads, letting a great answer graduate into permanent knowledge. Optional AI assistance helps organize titles, tags, and summaries, while the recommendation engine surfaces posts each member is likely to care about. The first account registered becomes admin, roles and permissions govern who can post or moderate, and community settings live in the admin panel rather than config files. One container starts everything with an embedded database and local file storage, and OpenAPI documentation is served from the same address. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MPL-2.0 licensed.

Haven gives your community a private chat server with voice calls, screen sharing, and end-to-end encrypted direct messages where friends join via invite link in their browser without installing apps or creating third-party accounts. Real-time messaging supports image uploads via paste and drag-drop, emoji reactions, replies, threads, typing indicators, @mentions with autocomplete, and inline GIF search through Tenor or GIPHY. Peer-to-peer WebRTC voice chat includes per-user volume sliders, mute and deafen controls, talking indicators, and screen sharing with picture-in-picture mode. Direct messages use ECDH P-256 key exchange with AES-256-GCM symmetric encryption where private keys never leave the browser, ensuring not even the server operator can read them. Twenty-plus visual themes with stackable effects including CRT scanlines, Matrix Rain, Cyberpunk Text Scramble, Snowfall, and Campfire Embers let users personalize the experience with configurable intensity sliders. Rich Presence integration shows what members are playing or listening to via Last.fm, Steam, and Spotify. A built-in bot API supports webhooks and custom slash commands, while Discord history import preserves channels, threads, forums, reactions, pins, and avatars. The Node.js server deploys via Docker Compose or a single batch file that auto-handles dependencies, SSL certificates, and configuration. 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.

Revolt gives communities the full Discord experience without ads, behavioral tracking, or subscription fees: servers with text and voice channels, direct messages, group conversations, roles, bots, and custom emoji at zero cost per user. The Rust microservices backend splits responsibilities across Delta for REST API and authentication, Bonfire for persistent WebSocket real-time event delivery, Autumn for file upload routing to MinIO S3-compatible object storage, and January for link preview proxy and embed generation. Voice chat operates through LiveKit with WebRTC audio streaming supporting multiple concurrent participants per channel. Server administrators configure hierarchical role-based permissions at the server, channel, and per-role level, controlling who can send messages, manage channels, kick members, and access moderation tools. Text channels support Markdown formatting, custom emoji, file attachments up to 20 MB, GIF search via Tenor integration, and message reactions. The bot API enables automated moderation, entertainment, and custom workflow integration with community-maintained libraries available in JavaScript, Python, and Rust. The TypeScript and Solid.js web frontend provides a responsive interface with theme customization. Docker Compose deployment spins up the complete stack including MongoDB for message and user storage, Redis for caching, and MinIO for attachments, providing complete data sovereignty over all conversations and files. 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.

Your team chat can be one executable on your own server: Campfire Rust runs rooms, direct messages, attachments, and search as a single binary that replaces the whole Ruby, Puma, Redis, Resque, and Thruster stack. Create rooms with access controls for projects, departments, or a private board discussion, and keep direct messages beside them for quick questions. File attachments arrive with previews, mentions pull the right person into a thread, and search finds the decision someone made months ago. Web Push notifications reach browsers and phones, so a quiet room still finds its people when it matters. Chatbots connect through a simple HTTP API for sending and receiving messages and attachments, which makes Campfire a home for build alerts, deploy notices, and support pings. Existing Campfire installs upgrade in place because the Rust binary reads the same SQLite database, storage layout, and signed cookies, with no data migration and no mass sign-out. Automatic TLS with Let's Encrypt certificates, HTTP/2, and Action Cable-compatible WebSockets are built in, and the whole system works on air-gapped networks that never touch the internet. Run it as your primary chat, as a backup for the day a hosted service goes down, or as a walled garden for executives and events. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.