Remote and distributed teams have become the norm across most industries – especially in the last few years. With less in-office face time, the need for always-on digital communication continues to intensify.
Messaging platforms like Slack have stepped in to fill this need with streamlined chat and collaboration capabilities. Adoption has skyrocketed, with Slack counting over 156,000 paying customers including the likes of Uber, Airbnb and Capital One.
However, while Slack offers a polished user experience, its limitations around flexibility, security and pricing have sent many organizations looking for alternatives. This is especially true for those dealing with highly sensitive data like in finance, government and healthcare.
Open source messaging and communication platforms provide solutions here. By self-hosting tools on their own infrastructure, teams gain:
✔️ Total data ownership
✔️ Advanced security configurations
✔️ Customizations matching unique needs
✔️ Long-term cost savings
But with dozens of options now available, narrowing down the best open source Slack alternatives can feel overwhelming.
As an online privacy professional and former cybersecurity analyst, I‘ve assessed numerous platforms on criteria like encryption, access controls, compliance depth, third-party audits, etc.
In this guide, I‘ll share my top recommendations on securing team communication with self-hosted open source software. I‘ll provide an overview of each tool, hosting recommendations, pricing estimates, and tips to simplify deployment.
Let‘s dive in!
Mattermost: Enterprise-Grade Security
Mattermost is an extremely secure and customizable open source alternative to Slack, made for devops teams with advanced self-hosting capabilities.
Comprehensive Messaging and Collaboration Features
Mattermost checks all the boxes for team messaging:
✔️ Public/private group chat
✔️ Direct messages
✔️ File sharing
✔️ Inline media previews
✔️ @mentions
✔️ Search
✔️ Bots & custom integrations
✔️ Mobile & desktop apps
It also goes far beyond chat to enable true workplace collaboration:
🚀 Screen sharing
🚀 Video calls
🚀 Status updates
🚀 Shared todo lists
🚀 Custom workflows
🚀 And more…
Plus, Mattermost‘s open source architecture allows adding just about any capabilities you can imagine.
Security Capabilities Meet the Highest Standards
As an infrastructure professional previously supporting large hospitals and government agencies, security is always my top evaluation criteria.
Mattermost exceeds even rigorous standards like HIPAA and FedRAMP with:
🔒 End-to-end encryption
🔒 LDAP/SAML single sign-on
🔒 Access controls
🔒 Session management
🔒 Intrusion detection
🔒 Regular security audits
It checks every box for messaging environments dealing with highly sensitive data.
The Mattermost team contributes heavily to security projects like OpenSSH, OpenSSL and Golang to ensure the platform leverages the latest encryption innovations.
Choice of Respected Hosting Providers
Since Mattermost is self-hosted, you‘ll need to set up infrastructure to run it.
Two top solutions I recommend are:
Kamatera: Kamatera delivers secure, high-performance managed hosting for Mattermost starting under $10/month. With 13 global data centers and a specialized open source hosting platform, they make deployment smooth and reliable.
A2 Hosting: A2 is well-known for blazing fast hosting, with solutions specifically optimized for chat tools like Mattermost. Their SwiftServer platform and comprehensive DDoS protection helps maintain reliable uptime. Pricing starts around $25/month for smaller teams.
Step-By-Step Guide to Deployment
Once infrastructure is in place, getting Mattermost up and running takes just a few steps:
1. Point DNS
Create an A record pointing your Mattermost domain to your server IP address.
2. Install Mattermost
Use your hosting dashboard to initialize a Mattermost installation via their one-click management tools.
3. Configure Settings
Adjust options like permissions, interface customization, notifications and more to suit your needs.
4. Create Channels
Set up channels for different teams, topics and projects.
5. Start Chatting!
Invite users, integrate tools like GitHub or Jira, and watch productivity and security soar!
With its robust access controls, encryption capabilities and extensive compliance support, Mattermost lets distributed teams collaborate securely at enterprise-scale.
Nextcloud: The Self-Hosted Productivity Platform
While Mattermost focuses solely on messaging, Nextcloud provides an all-in-one secure alternative to tools like Google Drive, Office 365 and Dropbox.
All Your Collaboration Tools in One Place
Nextcloud goes far beyond file storage and backup with a huge range of capabilities:
🗄️ Universal file access
☁️ Automated sync
💬 Secure chat
📅 Shared calendars
📞 Audio/video calls
📝 Online document editing
🤝 Project management
👥 Contacts & user directories
🔐 Password management
🔍 Activity dashboard
…and more. It‘s an ever-expanding platform!
With all tools pre-integrated yet modular, Nextcloud enables seamless, efficient team collaboration entirely under your control.
Leveraging the Latest Security Innovations
Nextcloud leverages many state-of-the-art security protections including:
🔒 End-to-end encryption
🔒 Brute force detection
🔒 Two-factor authentication
🔒 Intrusion prevention
🔒 Built on latest PHP and JavaScript security advancements
The platform also meets demanding compliance requirements like HIPAA, GDPR and more with:
✔️ Granular access controls
✔️ Comprehensive auditing
✔️ Rigorous penetration testing
This gives teams, especially in highly regulated industries, the confidence to use Nextcloud for all their communication and productivity needs.
Simple Setup Through Specialized Hosts
I recommend using an experienced host for Nextcloud deployments to save administrative headaches down the road:
Kamatera offers preconfigured Nextcloud plans to simplify getting started on its secure enterprise cloud platform.
RoseHosting goes a step further by providing not just hosting, but fully managed Nextcloud instances. Their Linux experts handle setup, maintenance, backups, updates and more so you can focus on usage rather than ops.
Launching Nextcloud in 4 Easy Steps
Here‘s how fast deploying a new Nextcloud instance can be:
1. Provision Infrastructure
Select a preconfigured Nextcloud hosting plan from Kamatera, RoseHosting or a similar provider. This creates and allocates all necessary cloud resources.
2. Configure Domain
Point your team domain to the cloud server IP using a DNS A record.
3. Login & Customize
Access your Nextcloud admin dashboard and begin enabling capabilities like Talk, Groupware, OnlyOffice and more. Tweak global settings to your preferences.
4. Start Collaborating!
Invite users, create spaces for projects/teams, and leverage real-time chat, document co-editing, shared calendars and more!
With tools unified on a single self-hosted platform, Nextcloud supercharges productivity and security.
Rocket.Chat: Feature-Packed Open Source Team Chat
Rocket.Chat is a rapidly growing open source alternative praised for its Slack-like experience coupled with more advanced capabilities.
Familiar Team Chat Interface
Employees transitioning from Slack will feel right at home with Rocket.Chat‘s slick web, desktop and mobile apps.
Core messaging features like:
💬 Channels
💬 Direct messages
💬 Replies
💬 Notifications
💬 Search
💬 Media embeds
💬 Emojis
…all work similarly to Slack. This makes onboarding intuitive.
Beyond Chat: Audio/Video Calls, Screensharing and More
While the chat interface strikes a familiar chord, Rocket.Chat stretches collaboration capabilities further with:
📹 Native video conferencing
🖥️ Screensharing
🤖 Custom bot development
⚙️ Zapier/IFTTT workflows
📡 Real-time translations
🔮 Visitor tracking
👪 Guest accounts
💼 Omnichannel customer support
These extras help centralize even more communication channels into Rocket.Chat‘s open source platform.
Enterprise-Scale Security and Ops
With organizations like Deutsche Bahn, Credit Suisse and the US Navy leveraging Rocket.Chat, its security protections and scalability hold up well:
🔐 SAML/SSO integration
🔑 End-to-end encryption
🛡️ Infrastructure role separation
⚖️ Compliance enablement (HIPAA, SOC2, GDPR)
😊 Bulk user provisioning
📈 Usage reporting
👮♀️ Moderation tools
🤖 Bot protection
This gives enterprise administrators confidence in centrally adopting Rocket.Chat across massive global workforces.
Rapid Setup on DigitalOcean‘s Cloud
Rocket.Chat recommends hosting on DigitalOcean for smooth deployments:
DigitalOcean makes installing Rocket.Chat a 1-click affair on its developer-friendly cloud infrastructure. Simply:
- Create a new Ubuntu Droplet
- Select Rocket.Chat from the Marketplace
- Run the auto-config scripts
With backend infrastructure handled by DigitalOcean, you‘re just minutes from launch!
For teams seeking an easy transition from Slack with more security and customization, Rocket.Chat is a prime choice.
Zulip – A Fresh Take on Team Chat
If you‘re looking for a uniquely streamlined approach to group chat, Zulip merits your attention.
Chat Reimagined for Productivity
The core of Zulip is its topic and thread-based messaging model (similar to email), a contrast to the free-flowing chaos of Slack.
Some key advantages this offers teams:
☑️ No constant context switching: Follow just the conversations important to you.
☑️ Discussions stay focused: No scope creep in channels.
☑️ No duplication: Each idea gets one thread.
☑️ Transparency: All team knowledge in one place.
☑️ Asynchronous-friendly: Catch up on own time.
☑️ Stay organized: Easy to file conversations.
It takes some adjusting from legacy chat but ultimately proves more orderly.
Custom Streams for Each Team
While unified across a company, users also create streams to follow custom flows:
🔀 Personal streams for 1:1 talks.
▶️ Temporary streams for projects.
📌 Private streams for sensitive subjects.
With full control over stream creation and topics, Zulip is easily customizable to any team structure or workflow.
Enterprise-Ready Self-Hosting
Zulip secures critical conversations by running directly on your servers:
🔒 LDAP/SAML single sign-on
🔐 Encrypted data transfer
🌐 Proxy support
🕵️♀️ User activity audits
👁️ Permission controls
Layering these protections over Zulip‘s topic-based chat model results in a uniquely productive and secure team platform.
Hassle-Free Deployments
Zulip provides single-command deployment on DigitalOcean or Kamatera cloud infrastructure.
For example with DigitalOcean, simply:
- Create a $10/month Ubuntu Droplet
- Clone your Zulip configuration
- Run the setup script
You‘re live with an efficiently hosted team chat service in practically minutes!
Let‘s Chat – Lightweight Self-Hosted Chat
For smaller teams on a budget, Let‘s Chat provides a handy self-hosted Slack alternative.
As a DIY open source solution, Let‘s Chat isn‘t loaded with bells and whistles.
But for basic private team communication, it delivers cleanly:
👥 Direct messages
💬 Multi-user chat
✉️ Persistent chat history
🔔Notifications
🔎 Search
All cleanly packaged in a simple node.js application customizable to your needs.
Host It Yourself for Maximum Privacy
Companies dealing with sensitive data often rule out third-party hosted chat tools, even when claiming robust encryption.
Let‘s Chat sidesteps this concern entirely by running locally on your servers.
You can tweak authentication (LDAP, SAML), enable SSL encryption, use firewall rules and more to dial-in protection to your policies and data classification levels.
While more hands-on, self-hosting gives you true data ownership.
One-Command Install with Docker
Thanks to its minimalist open source design, you can deploy Let‘s Chat with Docker in just minutes:
1. Install Docker
(if not already available)
2. Pull Let‘s Chat container
docker pull sdelements/lets-chat 3. Run container
docker run -d --name my-lets-chat sdelements/lets-chat4. Access UI & Configure
Find your server‘s IP to access web UI for adding users, channels etc. That‘s it!
So while it lacks bells & whistles of bigger platforms, Let‘s Chat makes a handy text chat platform completely under your control.
Remote work is here to stay. And with teams more distributed than ever, the ability to communicate and collaborate securely falls increasingly on software.
Yet today‘s widely used tools like Slack have accessibility benefits but can sacrifice data ownership, privacy and control.
That‘s why open source self-hosted alternatives are increasingly important for more organizations – especially those dealing with proprietary code, customer data or health records demanding strict need-to-know access.
Platforms like Mattermost, Nextcloud and the rest profiled here balance easy group chat features with enterprise-grade security protections not found in mainstream tools.
By owning your own communication infrastructure, you retain complete control over data access, encryption strengths, audit logs and more.
So if centralizing teamwork across a fast-scaling business while still locking down privacy, self-hosted chat and productivity tools are looking more appealing than ever.
What open source communication platforms are you using? Share your experiences below!
