I’ve been using Slack more and more and while I love it, the pricing is bit high for my current finances.

Basic features

  • chat rooms
  • private rooms
  • support file upload
  • link previews

Nice to have

  • edition of past messages
  • markdown formatting

Non important features

  • desktop or mobile clients

It goes without saying that any open source solution would be perfect.

  • Do you need past messages to be available forever? Do you need full-text search of past messages?
    – Nicolas Raoul
    Commented Oct 21, 2015 at 5:10

8 Answers 8



Miaou screenshot

Open source - runs on io.js

Basic features

  • chat rooms: yes
  • private rooms: yes
  • support file upload: yes
  • link previews: not sure

Nice to have

  • edition of past messages: yes
  • markdown formatting: yes

Non important features

  • desktop or mobile clients: web based only

Installation's slightly tricky since its currently in development, but it works great with ubuntu 14.04 lts and the nodesource io.js repos. I'm currently doing an install guide for it. However its possible for someone with an intermediate level of skill to install (though, I got a bit of help from the developer) it from scratch in an afternoon. Installation is also possible via Vagrant or Docker.

Live demo, actually used by several communities: https://dystroy.org/miaou

  • I'm the main author of Miaou and I see this QA today. Interested people are invited to come and chat on Miaou (in English or in French). Commented Feb 28, 2016 at 10:35


Rocket.Chat #dev channel

Open Source, Meteor alternative.

Existing Features

  • Free Open Source Software
  • Hassle free MIT license
  • BYOS (bring your own server)
  • Multiple Rooms
  • Direct Messages
  • Private Groups
  • Public Channels
  • Desktop Notifications
  • Edit and Delete Sent Messages
  • Mentions
  • Avatars
  • Markdown
  • Emojis
  • Transcripts / History
  • File Upload / Sharing
  • Unlimited Archive
  • I18n - [Internationalization with Lingohub]
  • Hubot Friendly - [Hubot Integration Project]
  • Media Embeds
  • Link Previews
  • LDAP Authentication
  • Face to Face Video Conferencing aka WebRTC
  • REST-full APIs
  • Remote Locations Video Monitoring
  • Native Cross-Platform Desktop Application
  • Native iOS Application
  • Native Android Application

In Progress

  • External popout window for chat with website visitor (like Zopim, Olark, LiveChat, SnapEngage)


  • Off-the-Record (OTR) Messaging
  • Full text search
  • Kerberos Authentication
  • XMPP Multi-user chat (MUC)


I am from the dev team of this project.


Let's chat







Vector, one of many Matrix clients (Pictured: Vector, one of many Matrix clients)

Open, federated protocol with many server and client implementations.

  • wanted to post an answer but its already here. It took me about 10 minutes to get synapse installed - the install instructions were simple. Vector was pretty simple too Commented Jul 8, 2016 at 15:10



  • needs a gihub account
  • support markdown
  • past messages can be edited before a certain delay
  • clients for desktop and phones (iOS, Android)
  • paid application with a free plan



You may submit feature request using uservoice



enter image description here

Not open source. Acquired by Atlassian a few years ago. XMPP based.

Basic features

  • chat rooms: yes
  • private rooms: yes
  • support file upload: yes
  • link previews: yes
  • hosted or on-premise: both available

Nice to have

  • edition of past messages: not yet
  • markdown formatting: not yet (although there is a Chrome extension for the web client)

Non important features

  • search archive: 25,000 messages on free plan (vs. Slack requires subscription after 10,000 messages)
  • desktop or mobile clients: both

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