Best Alternatives to Slack

Twist

Async team communication built around organized conversations

Twist is a team communication app from Doist built around asynchronous collaboration. It organizes discussions into channels and threads instead of relying primarily on continuous real-time chat. Teams can use threads for project discussions, announcements, questions, and updates, while direct and group messages handle shorter conversations.

Element

Open-source secure messaging and collaboration built on Matrix

Element is an end-to-end encrypted messaging and collaboration app built on the Matrix open standard. It supports direct and group messaging, rooms, file sharing, voice and video calls, threads, polls, and spaces. Teams can use the hosted service or run their own Matrix infrastructure. Element is designed around decentralisation, federation, and data ownership. The app is available free of charge, while Element Server Suite Pro adds professional features, support, and enterprise administration. Developers can also use Matrix APIs and integrations with services such as GitHub, GitLab, Jira, and webhooks.

Zulip

Open-source team chat organized around topics

Zulip is a team communication platform for startups, organizations, communities, and distributed teams. It combines streams with topic-based threading so separate discussions can stay organized within the same conversation space. The software is fully open source and can be used through Zulip Cloud or self-hosted on your own infrastructure.

Rocket.Chat

Secure team communication with self-hosted and cloud deployment

Rocket.Chat is a collaboration platform for channels, direct messages, threaded discussions, file sharing, search, voice, video, and customer engagement. It can be deployed on an organization's own infrastructure, hosted by Rocket.Chat, or operated in isolated environments for specialized requirements.

Mattermost

Open-source Slack Alternative for secure team communication

Mattermost is a collaboration platform built around channel-based messaging, file sharing, threaded discussions, audio calls, screen sharing, and search. It is aimed particularly at technical, operational, security, government, and other teams that need control over their collaboration infrastructure. The platform has an open-source Team Edition and commercial editions with additional enterprise capabilities. Its marketplace includes integrations for tools such as GitHub, GitLab, Jira, ServiceNow, Zoom, and Microsoft Teams.