6 Free Open Source Alternatives to Slack

Editor Ratings:

User Ratings:

[Total: 0 Average: 0]

Here are 10 free open source alternatives to Slack. You can use these open-source Slack alternatives for effortless team collaboration and communication. As they are open-source, you can get the source code from their official websites and tweak the interface and options as you desire. They offer various features like Slack such as group chat, private chat, file sharing, third-party integration, unlimited message search history, and so on. You can simply set up an account on these services and then start communication with your colleagues, employees, etc. seamlessly.

Slack is definitely one of the best enterprise communication tool, however, it does have some limitations in the free version. For example, you can only search 10,000 recent messages, integrations for up to 10 third-party apps, 5 GB space, etc. For this, we have already covered some Slack alternatives, but if you’re looking for open-source alternatives then you can find them in this post.

Now, let us get started.

Rocket.Chat:

Rocket.Chat is one of the best open source Slack alternatives which bundles dozens of useful features. The features include group chat, direct chat, files sharing, video call, and so on. That means it exhibits almost all the features of Slack, but with no limitations. You can create channels, invite team members, and chat with them with ease. It also offers some unique features like live chat, mailer, etc. To setup Rocket.Chat server, just one command is required.

Important Features of Rocket.Chat:

Cross-Platform: It is a cross-platform service which can be used on Windows PC, MacOS, Linux, and Web. Apart from that, you can also use it to communicate right from your iPhone and Android.
Channels: Similar to Slack, this one also allows you to create private and public channels for team communication. You can create unlimited channels with a custom name, invite different team members, etc.
Team Members: It allows you to invite and add unlimited team members. You can simply send invitations via email or add them manually to the “Users” list. You can then add the members to any channel or start a private chat with each of them.
Group Messages: You can use the channels created on Rocket.Chat for sending group messages. A channel can have multiple participants and anyone can collaborate or chat with the entire team.
Direct Messages: It also lets you have one on one chat with team members. You can use the “Direct Messages” feature to invite any member to a private chat.
Video Call: It comes with an option to make video calls to team members. You can either start a video chat from within a channel or during a private chat.
Audio Call: When you start a video call, if you only want to audio chat then you can simply disable video. This way you can have an audio conference or one on one audio chat with team members.
Voice Messages: It also comes with an option to send voice messages. You can simply press the “Record” button on the message field and then record and send the voice message.
File Sharing: You can share files like images, documents, audio, video, etc. with team members. The files can be shared during a group chat and private chat as well.
Message History: This one also provides unlimited message history. You can search for any message you want which you have had with others no matter how long it has been.
Integrations: It does support third-party integrations for almost all the apps supported by Slack. But, the catch is that you need to use Zapier for that. Remember, Zapier has limitations of the features in the free plan.
Data Import: This is a pretty useful feature which allows you to import data from Slack and HipChat. That means you can import data from these services and continue your conversations from where you have left. It even allows you to import CSV files to easily add contacts to the “Users” list.
Mailer: The mailer allows you to create custom emails which can be sent to the team members. You can either send the created email once or allow it for running daily to send the email automatically.
Live Chat: One of the unique features of Rocket.Chat is the “Live Chat”. Using this feature, you will be able to integrate a chat widget on your website and have conversations with the website visitors.

Know about Rocket.Chat in details.

Riot.im:

Riot.im is also a feature-rich and open source alternative to Slack. It offers various useful features including private chat, audio call, video call, file sharing, and more. You can use it to create chat rooms and invite team members for communication and collaboration. This one also exhibits almost all the features offered by Slack. To setup Riot.im, you can simply sign up for a new account on the Web or other supported platforms.

Important Features of Riot.im:

Cross-Platform: It is also a cross-platform Slack alternative. You can use it on your Windows PC, MacOS, Linux, Android, iPhone, and also on the Web. You don’t need to manually create a server to use it.
Chat Room: A chat room is similar to the Slack channel on which you can communicate with your team. It allows you to create unlimited chat rooms to have team communications.
Team Members: You can use it to invite unlimited team members for chat. You can add all the invited members to a single chat room or add them to separate rooms.
Guest Users: One of the useful features of this Slack alternative is that you can invite and ask guests to join conversations in chat room. That means if you want to invite someone for a single chat session, then you don’t need to add him/her as a permanent team member.
Team Chat: After adding team members to a chat room, you will be able to have a seamless team conversation. The best part is that you can have as many members as you want in a team chat.
Private Chat: In addition to team chat, Riot.im also allows you to do private chats with specific team members. You can choose any member you want and chat with him/her privately.
Video Call: This one also comes with the option to make video calls to team members. You can either video chat with a single user or conduct group chat with team members.
Audio Call: Apart from video calls, you can also make audio calls using this Slack alternative. It lets you either have an audio conference with multiple team members or have private audio calls.
File Sharing: Riot.im also allows you to share files like documents, images, audio, video, etc. with team members. You can upload unlimited files and share them during a team chat or private chat.
Message History: It provides unlimited message search history, which you can always find the conversations which you have had with your team members no matter how long it has been.
Integrations: It also supports third-party integrations like Google Apps, Giphy, Wikipedia, RSS, etc. Unlike Slack, it doesn’t support a large number of apps or bots.

Wire:

Wire is another open source Slack alternative which offers many useful features for team communication and collaboration. For example, you can have a group chat, send private messages, share files, video chat, audio chat, etc. It is one of the best services for having secure chat with the team. Unlike Slack, it doesn’t have any option to create channels, but you can create groups just by selecting multiple members for communication. You can setup a Wire account just by registering to it.

Important Features of Wire:

Cross-Platform: This Slack alternative is also a cross-platform service and is available for Web, Windows, MacOS, Linux, Android, and iPhone. That means no matter which device or operating system you’re using you will always be able to access Wire for team chat.
Team Members: This one also allows you to invite as many members as you want to your team. To invite members, all you gotta do is search them by their username or name. It also comes with the option to import and add contacts from your Google account.
Guest Users: Similar to Riot.im, this one also allows you to invite guests to ongoing conversations or for a private chat.
Group Messages: After you’re done inviting team members, you can simply start a chat and invite multiple members for a chat. This will automatically create a group where you can have group conversations.
Direct Messages: You can select any member you want to start a one on one chat. It allows you to send direct messages privately to any team member you want.
Video Call: It also comes with the option to make video calls to team members. Similar to Slack, it doesn’t allow you to start a video conference with your team. That means you can only make video calls to a single user at a time.
Audio Call: You can also make audio calls to team members. Unlike video calls, it allows you to have an audio conference with your team along with one on one audio chat.
Screen Sharing: As per the description on the homepage, Wire has the option for screen sharing. But, I wasn’t able to start a screen sharing session.
File Sharing: It allows you to upload and share various files like images, audio, documents, etc. with team members. You can share files during a private or group chat.
Message History: It also offers unlimited chat history. That means it doesn’t matter when you have had a chat with the team members, you can always find the conversations using the search function.
Timed Message: It is one of the unique features of this Slack alternative which allows you to schedule messages. It allows you to schedule messages for 5 secs, 15 secs, 30 secs, 1 minute, 5 minutes, or even 1 day.

Mattermost:

Mattermost is also one of the best open-source Slack alternatives which you can use for team collaboration and communication. The interface of Mattermost is quite similar to that of Slack. It offers various features like group chat, file sharing, one on one chat, slash commands, etc. All the useful features of Slack are present, but some are not like video calls, audio calls, etc. The account on Mattermost can be easily setup by configuring the server.

Important Features of Mattermost:

Cross-Platform: Mattermost is a cross-platform application and you can use it on the Web, Mac, Windows, Linux, iPhone, and Android.
Channels: In Mattermost, you can create public and private channels for team communication. Similar to Slack, it allows you to create custom channels and then invite team members for collaboration and for discussing topics.
Team Members: It lets you invite as many users as you want to channels. You can either share an invitation link or invite via email. The users can click on the invitation link and join your team.
Group Chat: For group chat, you can either use the public channels or private channels. In any channel, you can add multiple users and then communicate with them within the channel.
One on One Chat: It not just only lets you have group chats, but also one on one chats. You can choose any team members and then have a private conversation with him/her.
Slash Command: Similar to Slack, this one also supports slash commands in the message field. Some of the actions which you can perform using the slash commands are set your status, display text as a code block, collapse image previews, etc.
File Sharing: This open-source alternative to Slack also allows you to upload and share files. You can share files like documents, audio, images, etc. Files can be shared during a private chat or group chat.
Data Import: This is one of the best features of Mattermost which allows you to import data from Slack. That means the messages which you have had with your team on Slack can be important and continued in Mattermost.
Mentions: This one also allows you to mentions anyone in the messages you send on channels. The team members can also mention you in messages which you can see in the “Mentions” tab.
Flagged Posts: You can flag messages and comments during group and private chats. This allows you to mark messages for quick follow-up. Flagged items can be seen in the “Flag” tab and are private to you only.
Message History: All the messages in Mattermost are automatically archived and becomes searchable. It lets you search unlimited message history without the time limit.
Reports: You can see reports for active users with posts, daily active users, monthly active users, and more.
Integrations: Currently, you can only integrate JIRA and WebRTC. But, it also allows you to add custom integrations using WebHook.

Gitter:

Gitter is another useful open source alternative to Slack for team communication and collaboration. It is primarily for teams of developers to communicate with each other for the coding purpose. Unlike Slack, it doesn’t have many features like video call, audio call, etc. and can only be used to chat with a team. As it is mainly for developers, it comes with a markdown editor mode to write and collaborate on code. Similar to Wire, you can simply create an account on Gitter to start using it.

Important Features of Gitter:

Cross-Platform: It is a cross-platform service and you can use it on Windows, Mac, Linux, Android, and iPhone.
Community: You can create communities in Gitter to have team conversation and collaborate. It allows you to create as many communities (public and private) as you want and then invite users to them. It even allows you to explore and join tons of other public communities and join their room for participation.
Room: Within a community, you can create room such that you can divide departments and invite users accordingly. A room can either be public or private.
Team Members: After creating a room inside any community, you can go ahead and start inviting users via email or sharing the room URL. You can add as many members as you want to a single room.
Group Chat: After adding members to a room, you will be able to start communication and collaborating with them on any topic. The messages sent in a room will be visible to all members and they can also send replies with their own messages.
Private Chat: Gitter also comes with the option to private chat with specific team members. You can simply choose any member you want and start exchanging private messages.
Chat Modes: There are two different chat modes in Gitter. One is “Chat Mode” and the other is “Compose Mode”. In the chat mode, you will be able to chat with others as you normally do in Slack. Whereas, in the compose mode, you will be able to write code with markdown editor and submit it in the room.
Message History: You can search unlimited messages without worrying about the time of conversations.
Integrations: Gitter supports third-party integrations for various apps like GitHub, BitBucket, Trello, Heroku, GitLab, and more. No apps limitation.
Night Mode: It comes with a dark theme which you can use to toggle on the night mode. This can come handy to reduce eye strain when you’re using Gitter at night.

Zulip:

Zulip is another open source Slack alternative with various features including file sharing, private chats, third-party integrations, group chats, and more. However, it doesn’t have a few features which Slack does, like video calls, audio calls, and screen sharing. Zulip allows you to simply sign up for a new account and then share the account URL with others for joining your team, as you do on Slack.

Important Features of Zulip:

Cross-Platform: This team communication service is also a cross-platform service which you can install and use on Mac, Windows, Linux, Android, and iPhone. In addition to that, it also offers a web version such that you won’t need to download anything to use it.
Streams: Similar to Slack channels, you can create streams on Zulip. It lets you create public and private channels and invite team members to them for a chat. The messages sent to any stream can be seen by all who are participants in that stream.
Team Members: You can invite unlimited team members to Zulip. To invite team members, simply open and stream you want and then send invitations via email.
Group Chat: Once you’re done inviting and adding members to a stream, you will be able to start a group chat in the stream. You can have multiple group chats just by creating separate streams.
Private Chat: Apart from group chats, you can also have one on chats with specific team members. You can send private messages to any team member you want.
File Sharing: This one also has the option to upload and share files with others. But, do note that the limit of free space in Zulip is up to 1 GB. That means you can only upload files of 1 GB for sharing during a chat. If you’re running out of space the deleting the existing files will free up space.
Drafts: It is a very useful feature using which you can draft messages and send them later to team members. You can create and save as many draft messages as you want.
Mentions: The mentions can be used to tag a specific user in a message. It even comes with a separate “Mentions” section where you will be able to see all the messages in which team members have tagged you.
Starred Messages: If you want to separate store important message, then you can use the “Star” feature. It allows you to favorite messages and then access them quickly from a separate tab called “Starred Messages”.
Message History: This Slack alternative also provides unlimited message search history. You can find any message you want which you have had earlier with team members.
Integrations: Similar to Slack, this one also allows you to integrate more than 60 third-party apps. Apart from that, you can also use IFTTT, Zapier, and Hubot to integrate tons of other apps. No limitations on the number of apps.

Closing Words:

So, these are some of the best open source alternatives to Slack. Personally, I think all of them are pretty good and offer decent features which you can use for free. However, if you’re looking for an open source team communication service with bundles of advanced features, then start using Rocket.Chat or Riot.im right away.

Try these open source Slack alternatives and let me know which one you liked in the comments.