The deciding question
Who can read a direct message
Enclessa
End-to-end encrypted with MLS. The server holds no key for the message.
Slack
- Sender
- Service, with your keys
- Recipient
Enterprise Key Management lets you control the keys; the service still processes content.
The case for Enclessa
Reasons, argued rather than asserted
Customer-managed keys are not end-to-end encryption
Holding the key yourself is a real control, but not the same as the service being unable to read the message. In Enclessa the server never has a key for an encrypted room.
European hosting on every plan
The service runs in the European Union for every customer, not only the top tier.
The work, not only the talking
Boards, GitHub sync, time tracking and personnel records share one platform and one permission model.
A retention policy you set
History is kept by your retention rules, not by your plan.
Side by side
Enclessa and Slack, point by point
| Dimension | Enclessa | Slack |
|---|---|---|
| What is published for review | Architecture, data model, OpenAPI surface and encryption design | Product documentation and a trust centre |
| End-to-end encryption | Direct and group direct messages, MLS per RFC 9420 | Not offered. Enterprise Key Management provides customer-controlled keys, with the service still processing message content |
| Hosting | European Union; a dedicated deployment on Enterprise, operated by us | Operated by Salesforce, with regional residency options on higher tiers |
| Message history | Retained per your own retention policy | Historically limited on lower tiers; check the current plan terms |
| Third-party apps | None. First-party modules only, no runtime third-party code | An established third-party app directory |
| Included modules | Task boards, GitHub sync, time tracking, HR records | Available through third-party apps |
| Video calls | Group calls with screen sharing, lobby and host controls | Huddles, plus integrations with dedicated meeting products |
| Leaving | Full organisation export; documented data model and OpenAPI | Export tooling varies by plan |
Statements about other products come from their own public documentation and describe the position as last checked on 18 August 2026. Vendors change what they offer; check the current documentation before making a decision on the strength of this page.
In fairness
Where Slack is the better choice
- Your workflow depends on the app directorySlack’s ecosystem is its strongest asset, and Enclessa runs no third-party code. If a Slack app is central to your work, that is decisive.
- You work across many external organisationsShared channels between companies are something Slack does well and Enclessa does not offer.
- Familiarity has a real cost for youMost people already know Slack. If rollout budget is thin and confidentiality is not a driver, that is worth money.
FAQ
Enclessa vs Slack: questions
- Enclessa is not one: it is a commercial hosted service and its source is not published. Mattermost is the best-known open-source option, oriented towards self-hosting. In place of readable source, Enclessa publishes its architecture, data model and OpenAPI surface, and encrypts direct messages with MLS.
- Slack does not offer end-to-end encryption of messages. Its Enterprise Key Management feature lets a customer control the encryption keys, but the service still processes message content. Enclessa encrypts direct and group direct messages end to end with MLS, so the server holds no key that opens them.
Other comparisons
Compare with something else
Bring your team over this afternoon
Free for up to 10 people, with encrypted direct messages and video calls. No payment card, no time limit, no server to run.
For businesses and organisations only — not available to consumers.