Free Alternative to Slack

Discord started as a gaming platform but has evolved into a surprisingly powerful business communication tool. What began as a way for gamers to coordinate raids has become the secret weapon for developer teams, open-source projects, and tech-savvy startups. The core advantage is simple: completely unlimited message history on the free tier, forever.

No 90-day limit like Slack's free plan. Add to that always-on voice channels where team members can drop in and out naturally, excellent screen sharing capabilities, and a mobile app that actually works well. The interface feels less corporate than Slack, which some teams love and others find unprofessional, but the functionality is undeniable.

Major open-source projects like Vue.js, Electron, and many indie hacker communities have made Discord their primary communication hub. The platform supports bots and webhooks for automation, though the ecosystem is different from Slack's business-focused integrations. File sharing has a 100MB limit on the free tier, but Nitro ($9.99/month for the whole account, not per user) bumps that to 500MB if needed.

Mattermost is the closest thing to Slack you can self-host, and that's by design. The interface is intentionally familiar—channels on the left, conversations in the middle, thread panel on the right—making migration almost seamless for teams switching from Slack. It's open-source software trusted by security-conscious organizations including the U.S. Department of Defense, and gives you complete control over your data infrastructure.

The free self-hosted version has no user limits whatsoever and includes features that Slack charges premium prices for: unlimited message history, advanced search with filters and modifiers, guest access, and extensive API access. Mattermost integrates with over 700 third-party tools and services, and you can build custom integrations using webhooks, slash commands, and plugins. The platform supports compliance exports for regulatory requirements, making it popular in healthcare, finance, and government sectors.

Self-hosting means you need infrastructure (a virtual machine, Docker container, or Kubernetes cluster), but deployment is well-documented and straightforward. If you don't want to manage infrastructure, Mattermost Cloud starts at $10 per user per month, which is competitive with Slack while offering better control and compliance features.

Zulip takes a radically different approach to team communication with its unique topic-based threading model. Unlike Slack where conversations in busy channels become chaotic threads, Zulip organizes every message into streams (similar to channels) and topics (like email subject lines). This seemingly small change makes a massive difference for distributed teams working across time zones.

You can jump into a conversation from three days ago, catch up on the specific topic thread, and contribute meaningfully without wading through hundreds of unrelated messages. The interface feels more like a well-organized email client than a chat app, which takes some adjustment but pays dividends for async work. Zulip is 100% open-source with no proprietary enterprise version—the same codebase powers both the free cloud tier (10,000 searchable messages) and unlimited self-hosted deployments.

The platform includes over 90 native integrations including GitHub, Jira, Sentry, and custom webhooks. Code snippets, LaTeX math equations, and markdown formatting are first-class citizens. Dropbox, Akamai, and thousands of open-source projects use Zulip specifically because it handles asynchronous communication better than any alternative.

Element is the flagship client for the Matrix protocol, representing a fundamentally different approach to communication: decentralized and federated like email, but with modern chat features and end-to-end encryption by default. Unlike Slack's proprietary walled garden where all data lives on Slack's servers, Matrix is an open standard that anyone can implement. You can host your own Matrix server (called Synapse) and still communicate seamlessly with users on other Matrix servers—or even bridge to Slack, Discord, Teams, IRC, and Telegram rooms.

This makes Element a potential universal communication hub. The security model is exceptional: messages are end-to-end encrypted using the Olm and Megolm cryptographic ratchets, the same technology Signal uses. France's government uses Matrix for sensitive state communications.

The free tier on Element.io includes up to 200 users with encryption, unlimited message history, and voice/video calls. For larger organizations or complete control, self-hosting Synapse is free and well-documented. The learning curve is steeper than Slack, and the ecosystem is smaller, but for teams prioritizing privacy, sovereignty, and avoiding vendor lock-in, Element is unmatched.

Rocket.Chat stands out by combining internal team messaging with omnichannel customer communication in one platform. This means you can handle not just team chat, but also customer support via email, SMS, Facebook Messenger, WhatsApp, and live chat widgets—all from the same interface. It's fully open-source and built with compliance in mind, featuring GDPR, HIPAA, and FINRA capabilities out of the box, which explains its popularity in healthcare, government, and financial services.

Self-hosting is completely free with no user limits, and you get features that would cost hundreds per month on Slack: unlimited message history, guest access, audio/video conferencing (via Jitsi integration), screen sharing, and granular permission controls. The platform is highly customizable—you can modify the source code, create custom themes, and build apps using the extensive API. Rocket.Chat also offers a marketplace with dozens of apps extending functionality. For teams that need both internal communication and customer-facing support channels, Rocket.Chat eliminates the need for separate tools like Intercom or Zendesk Chat.

Microsoft Teams deserves consideration for one simple reason: if you're already paying for Microsoft 365, it's included at no additional cost. Even without M365, the standalone free tier is surprisingly generous—unlimited chat history, group meetings up to 60 minutes, file storage (5GB per user), and integration with Office web apps. Teams truly shines when your organization lives in the Microsoft ecosystem: editing Word documents collaboratively, reviewing Excel spreadsheets, managing Outlook calendars, and storing files in SharePoint all happen seamlessly within Teams.

It's also the only major Slack alternative with enterprise-grade video conferencing built directly into the platform, supporting up to 300 participants in the free tier. The integration with other Microsoft services is both its greatest strength and biggest weakness—it works brilliantly if everyone uses Microsoft tools, but feels clunky if your team prefers Google Workspace or other platforms. Teams has improved significantly since its rocky 2017 launch, though it remains resource-heavy and can slow down older computers.

Pumble positions itself as the true free Slack alternative by removing the artificial limitations that plague other free tiers. While Slack's free plan restricts you to 90 days of history and limits integrations, Pumble offers unlimited message history, unlimited users, unlimited channels, and 10GB of file storage—all completely free. This makes it ideal for growing teams that don't want to worry about hitting arbitrary limits.

The interface is clean and familiar to anyone who's used Slack, with channels, direct messages, threads, and @mentions working exactly as expected. Pumble includes unlimited 1-on-1 video and voice calls on the free tier, though group calls require the paid plan ($2.49 per user per month when billed annually). The platform supports integrations via webhooks and Zapier, though the native integration ecosystem is smaller than Slack's.

For teams that just need solid, reliable team chat without paying per seat, Pumble delivers exactly that. It's particularly popular with bootstrapped startups, nonprofit organizations, and small businesses where every recurring expense matters.

Chanty differentiates itself with a built-in task management system called Teambook, eliminating the need for separate project management tools for many teams. Convert any message into a task with a single click, assign it, set due dates, and track progress without leaving the chat interface. The free tier includes unlimited message history (unlike Slack's 90-day limit), but caps teams at 5 users, making it suitable for very small teams or departments within larger organizations.

Voice and video calls are included even on the free plan, along with screen sharing and searchable conversation history. The interface is clean and straightforward, prioritizing simplicity over feature bloat. Chanty integrates with popular tools like Trello, Asana, GitHub, and Zapier, though the ecosystem is smaller than Slack's thousands of apps.

The paid plan at $3 per user per month (billed annually) is more affordable than Slack while removing the 5-user limit. For small teams that find themselves constantly switching between Slack and a task manager, Chanty's integrated approach can significantly streamline workflows.

Twist was built by the team behind Todoist specifically to combat the always-on, notification-heavy culture that Slack encourages. It's designed for asynchronous communication where thoughtful responses matter more than immediate replies. Every conversation in Twist is organized into threads within channels, and threads stay separate—no mixing of topics like in traditional chat.

Messages are expected to be longer and more considered, reducing the constant ping-pong of short messages. Twist intentionally lacks presence indicators (no green dots showing who's online) and encourages teams to disable notifications and check in a few times per day rather than staying constantly connected. The free plan includes unlimited users and channels but limits searchable message history to 5,000 messages—sufficient for small teams but restrictive as you grow.

Twist integrates with fewer tools than Slack, which is partly intentional to avoid distraction. The platform explicitly doesn't include voice or video calling, expecting teams to use dedicated tools when synchronous communication is truly necessary. For teams drowning in Slack's constant interruptions and trying to build a calmer work culture, Twist offers a radically different philosophy.

Flock combines team messaging with built-in productivity features including shared to-do lists, polls, reminders, and note-taking. The free tier offers 10,000 searchable messages (better than Slack's 90 days but still limited), unlimited integrations, and 5GB of file storage. What makes Flock interesting is the tight integration of productivity tools—you can create polls directly in chat, set reminders for team members, and maintain shared to-do lists without switching apps.

The platform includes unlimited 1-on-1 and group video calls even on the free plan, along with screen sharing. Flock integrates with Google Drive, Dropbox, Asana, GitHub, and other popular services. The interface is clean and approachable, though it lacks the polish of more established alternatives.

The paid plan at $4.50 per user per month (billed annually) is competitively priced and unlocks unlimited searchable messages. Flock works well for small to medium teams that want lightweight productivity features integrated with chat without paying for heavyweight project management software.