Mattermost

Open source, private cloud Slack-alternative, Workplace messaging for web, PCs and phones. MIT-licensed. Hundreds of contributors. 14 languages. Secure, configurable, and scalable from teams to the enterprise

PRICING

Free tier available. Paid accounts start from $3.25 per user/per month (billed annually)

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Key Features

Workplace messaging with search and integrations
1-1 and group messaging
Compliance reporting is available

Great for

Share files with team members
Advanced security is available, you can enable Multi-factor authentication and encrypted push notifications
Centrally manage thousands of users and hundreds of teams with advanced synchronization and automation of users and roles

Be aware that

Does not support video or phone calls from within the platform

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