Mattermost

27958 stars

Mattermost is an open source, self-hosted, private cloud messaging solution compared to Slack which does not have the option to self-host. Security concerns still remain the number one barrier to a cloud computing deployment. With Mattermost, compliance is easy as the data does not leave the customer's premises. It’s perfect for businesses that want to keep their messaging app under tight control. Slack offers 2000+ integrations which covers all applications businesses use. While Mattermost has 100s of integrations as well, the use-case coverage is still limited when compared to Slack.

Commerical Alternatives

Slack

Features

Self-hosted one-to-one and group messaging, file sharing and search
Guest accounts
Custom branding
Unlimited search history
Multi-language translation
Unlimited integrations
Active Directory / LDAP Group sync
Native apps for iOS, Android, Windows, Mac, and Linux Client apps for desktop and mobile.
Multi-factor Authentication
Access control policies
Automated compliance export
Single sign-on
Read-only Announcement channels
Elasticsearch

Pricing

Mattermost charges $10 /user/month for the cloud version, and price ranges from $0/ user/month to $8.5/user/month for the self-hosted version depending upon feature requirements.

Self hostable

Yes

Customers

AIG, SAP, Samsung, Bosch, Deloitte, BNP Paribas, Affirm

G2 Score

4.2/ 5 (250 reviews)

Reviews (Snippets from G2)

Pros

This is the most comprehensive chat forum I have ever seen used in a work environment, which is safe to use for both company management and employees.
I get the full history of all chats, can control the message flow via own server, so full control.
You can start a Zoom call with just 1 click.
You can customize the color scheme as you like. It feels great to be able to choose how things look, rather than having an old, gray website.
The search engine function is also extraordinarily powerful and very quick.
Easy channel layouts and allows you to access your chats and information through multiple options.

Cons

Installing the server is not trivial and requires system administration skills.
I go through hell when there is no internet connection since, Mattermost lacks capabilities for functioning while not connected to the internet.
Most of the Top Level Plugins are missing as in Slack.
I wish they had a drag and drop function for files and pictures into the chat.