Best private Slack alternatives for teams that need real privacy

Why chat, specifically, deserves the scrutiny Documents get reviewed, archived and sanitised. Chat is unedited: incidents, negotiations, salaries, roadmaps, customer complaints and the reasoning behind every decision. It is the highest-value single dataset a company holds, and in most companies it sits in a product that can read it.

What "private" means across the options - **Mainstream chat with enterprise controls.** Retention policies, DLP, compliance exports. The vendor can still read history; the controls govern how that capability is used. - **Self-hosted chat (e.g. Mattermost, Rocket.Chat deployments).** You control the server. Message content is typically readable on that server, so privacy depends on your operations rather than the vendor's. - **Federated end-to-end encrypted chat (e.g. Matrix/Element deployments).** Real end-to-end encryption, at the cost of device-verification and key-backup complexity that non-technical teams frequently mishandle. - **Hosted zero-knowledge workspaces.** End-to-end encryption with per-recipient sealed keys, operated for you, with no server-side plaintext to index or export.

The five tests worth running before migrating 1. **The admin test.** Ask the vendor whether an administrator can read a private channel. Vague answers are answers. 2. **The offboarding test.** Remove a member and ask what happens to the group key. 3. **The search test.** Search for a phrase from three months ago on mobile. If search is unusable, people will keep using the old tool. 4. **The speed test.** Switch channels twenty times on a mediocre connection. Latency drives shadow IT more than any policy. 5. **The attachment test.** Send a 2 GB file. Watch where it actually goes.

What you give up with genuine end-to-end encryption Bots and integrations that read messages, provider-side compliance export of plaintext, server-side search, and link previews generated centrally. If your regulator or policy demands provider-held readable archives, end-to-end encryption is genuinely incompatible with that requirement, and you should know it before the pilot rather than after.

What you gain A workspace export from the vendor is ciphertext. A compromised integration cannot exfiltrate history it never sees. An ex-employee's cached key stops opening new content the moment they are removed. And the conversation about "who can read our chat" becomes a short one.

Where DRIVUNO fits DRIVUNO combines encrypted channels, DMs, threads, tasks, calls and screen share with an encrypted team drive, mail and a secrets vault in the same key hierarchy — each message sealed for exactly its recipients, search served by blind indexes computed on your device, and no self-hosting to operate. The trade-offs above apply to us as much as to anyone else, and we would rather you test them in a pilot than discover them later.