Microsoft Teams is Microsoft's enterprise collaboration platform launched in 2017, with 320 million+ monthly active users. It supports up to 1,000 participants per meeting and deeply integrates Microsoft 365 and Copilot AI as a core tool for modern work.
Ryver is a U.S.-based team collaboration platform that combines chat, topics, and task management in one app, replacing a Slack and Trello combination. Starter starts at $69/month with unlimited messaging, task boards, and voice/video calls.
Fleep is a team chat and project collaboration tool founded in Tallinn, Estonia in 2014, merging conversations, tasks, files and issue tracking into one thread. The free plan lets small teams start immediately.
Zulip is an open-source team chat platform created in 2012 and released under Apache 2.0 in 2015, maintained by Kandra Labs and headquartered in San Francisco, United States. Its unique Stream+Topic threaded model makes async communication efficient and orderly, with unlimited users and self-hosting on the free plan.
Rocket.Chat is an open-source team communication platform initiated in 2015, offering free self-hosting, end-to-end encryption, and Matrix federation, officially serving 12M+ users and 100,000+ organizations - a Slack alternative for organizations that prioritize data sovereignty and compliance.
Google Chat is the team messaging tool built into Google Workspace, supporting 1-on-1 and group chats with threaded discussions, deeply integrated with Gmail, Drive, and Meet, and supporting bot automation.
Chanty is a lightweight team chat platform founded in 2017 in Ukraine; the free plan supports 10 members with unlimited message history, and the paid plan starts at about $3/user/month with AI summaries and Kanban tasks, a high-value Slack alternative.
Brosix is a peer-to-peer encrypted instant messaging platform founded in Bulgaria in 2006, using AES-256 encryption and a private-network architecture to deliver chat, voice/video, screen sharing and remote control for teams.
Mattermost is an open-source team collaboration platform founded in 2014 in Palo Alto, California, supporting private deployment with unlimited users. Adopted by NATO and the US Department of Defense, its free edition includes 10GB file storage for data-security and compliance scenarios.
Flock is an enterprise team messaging and collaboration platform launched in 2014 that combines group chat, HD video conferencing, task management and 150+ app integrations. The free plan supports 20 people; Standard is $4.50/user/month.