There is a very real, ongoing tension within the open-source community. Many open-source purists and contributors agree: using a proprietary, closed-source platform to build an open-source project feels deeply contradictory.
This exact issue is a source of constant debate in the technology world. The reliance on Slack comes down to a pragmatic trade-off between pure open-source ideology and operational efficiency.
The Contradiction in Principles
The “Walled Garden” Problem: Slack’s source code is secret, and its data is stored on centralized, private corporate servers.
Data Lock-In: It is difficult to completely archive, search, or move years of community knowledge out of Slack without paying or hitting API limitations.
Barriers to Entry: To join the conversation, developers must agree to Salesforce’s corporate terms of service and privacy policy.
Why the Community Tolerates It (The Pragmatic View)
Familiarity and Friction: Most developers already use Slack for their day jobs. Forcing volunteers to install a niche, open-source chat client creates “friction” that reduces the number of people willing to contribute.
Maintenance Overhead: Hosting an enterprise-grade chat alternative (like Mattermost or Matrix) for tens of thousands of global users requires massive server infrastructure, security patching, and constant moderation. Slack handles all of this for free.
Focusing on the Product: Many leadership teams argue that it is better to spend limited non-profit engineering hours improving the WordPress software itself, rather than managing a self-hosted chat server.
They Aren’t Alone (But the Tide is Shifting)
WordPress is not the only giant to make this compromise; major open-source ecosystems like Kubernetes and Linux foundations have heavily relied on Slack or GitHub.
However, the hypocrisy bothers many projects enough that they have left. For example, Fedora, GNOME, and Mozilla famously migrated away from proprietary tools to open-source, decentralized alternatives like Matrix or Element to stay true to their core ethos.
Why Matrix or Mattermost work as open-source alternatives, and other projects successfully migrated away from Slack?
Matrix and Mattermost work as open-source Slack alternatives because they offer complete data sovereignty, self-hosting control, and avoidance of vendor lock-in or per-seat cloud pricing. Numerous tech projects, crypto foundations (like Decentraland and Golem), and privacy-focused government agencies have migrated away from Slack to cut costs and meet strict compliance mandates.
Why Mattermost and Matrix Work So Well
- Mattermost: Functions as a direct, channel-and-thread clone of Slack. It provides drop-in API compatibility, bulk workspace data imports, and deep DevSecOps integrations (GitHub, Jira) while remaining safely behind corporate firewalls.
- Matrix: Operates as an open, decentralized communication protocol (using clients like Element). It enables end-to-end encryption, independent server federation, and robust bridges that link directly into legacy Slack or Discord rooms.
Migrating Away from Slack
- Open Source / Crypto Coalitions: Early waves of decentralized autonomous organizations and open-source software projects (such as Golem, Santiment, and Aragon) famously ditched Slack for self-hosted tools to align their communication infrastructure with open-source principles.
- Government & Enterprise: Public sector bodies (especially across the EU) migrate to platforms like Mattermost or Matrix to evade US jurisdiction issues tied to the CLOUD Act, ensuring total regional data residency and compliance.