Alternatives to Slack

Secure team communication from Switzerland, France and the United Kingdom. End-to-end encryption, self-hosting via Matrix, no US cloud lock-in, and GDPR-compliant data processing agreements for organisations.

4 alternatives
European sovereign messaging
Updated 2026

Element

Matrix protocol, self-hostable

In detail

Slack compared to European team messengers

Slack Technologies was acquired in 2021 by Salesforce, Inc., a US company headquartered in San Francisco. This subjects Slack to the CLOUD Act (2018) and the Stored Communications Act. US authorities can compel the disclosure of messages, files and metadata regardless of whether they are stored in EU data centers (Frankfurt, Dublin). The Schrems II ruling (2020) found that US surveillance laws such as FISA Section 702 conflict with the GDPR.

Slack does not provide end-to-end encryption by default. Messages are encrypted in transit (TLS) and at rest (AES-256), but Slack holds the keys. This enables server-side search, compliance exports and AI features, but it also means Slack staff, Salesforce and, under subpoena, US authorities can access content. Slack Enterprise Key Management (EKM) offers customer-controlled keys but is only available in the most expensive enterprise tiers.

Slack has changed its pricing model several times: in 2022 message history retention in the Free plan was reduced from unlimited to 90 days; in 2024 Pro pricing was raised to €8.75 per user per month (annual billing). For a team of 50 people, that is more than €5,000 per year. European alternatives such as Element (Matrix) and Olvid offer self-hosting without ongoing license fees, or unlimited retention in free tiers.

European team messengers are predominantly open source: Element is based on the Matrix protocol (Apache 2.0), Threema Libre and the Threema client code are published under AGPL, and Olvid is open source and CSPN-certified by the French cybersecurity agency ANSSI. Government agencies in France and Germany (Bundeswehr, BWI) use Matrix and Element in production. For organisations with compliance requirements, self-hosting via Matrix is an established option that is not available with Slack.

Quick Compare

Provider	Country	Open Source	Price (From)
Stackfield	Germany	No	Starter EUR 9 · Business EUR 14 · Premium EUR 18 · Enterprise EUR 28 per user/month (net). 14-day free trial.
Element	United Kingdom (EU subsidiaries in DE/FR)	Yes	Community free (self-hosted) · Enterprise on request
Threema	Switzerland	Yes	One-time €6 · Threema Work from €3/user/mo
Olvid	France	Yes	Free (personal use) · Business from €9.90/user/month

European alternatives

4 alternatives in detail

Stackfield

Germany

Project management and team collaboration with end-to-end encryption

End-to-end encryption (AES-256, RSA-2048), client-side
Task and workflow management with timelines
Team chat, rooms and discussions

Platforms

Starter EUR 9 · Business EUR 14 · Premium EUR 18 · Enterprise EUR 28 per user/month (net). 14-day free trial.

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Element

United Kingdom (EU subsidiaries in DE/FR)

Decentralized messenger based on the Matrix protocol

Federated Matrix protocol, no central control
End-to-end encryption (Olm/Megolm)
Self-hosting or managed EU cloud available

Platforms

Open Source

Community free (self-hosted) · Enterprise on request

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Threema

Switzerland

Messenger without mandatory phone number registration from Switzerland

No phone number required, fully anonymous
End-to-end encryption for all messages
No metadata storage

Platforms

Open Source

One-time €6 · Threema Work from €3/user/mo

Visit Website → View details →

Olvid

France

ANSSI-certified messenger without central user database from France

ANSSI-certified (CSPN)
No phone number or email required
Proprietary cryptographic protocols, independent of Signal protocol

Platforms

Open Source

Free (personal use) · Business from €9.90/user/month

Visit Website → View details →

Frequently asked questions

Are European Slack alternatives GDPR compliant?

Element (UK, Matrix protocol), Threema (Switzerland) and Olvid (France) operate under EU data protection law or in countries covered by an adequacy decision. Self-hosting via Matrix/Element additionally enables full data sovereignty in your own data center.

Which alternative offers the strongest end-to-end encryption?

Threema, Element and Olvid use end-to-end encryption by default for all messages. Olvid is ANSSI CSPN-certified and is used by the French government. Element/Matrix supports encrypted rooms of any team size with cross-signing across devices.

Which solution is suitable for businesses?

Element Server Suite offers enterprise editions with Active Directory integration, compliance logs, cross-signing and federation. Threema Work has its own enterprise edition with MDM integration. Olvid offers business plans and is used in the French public administration. For teams with self-hosting requirements, Matrix/Element is the established choice.

Can I migrate Slack data to a European solution?

Slack offers a workspace export (JSON) on Pro and above. Element and Matrix support import bridges that can ingest channels and messages. A full migration usually requires a transition phase in which both systems run in parallel.

Do video and voice calls work?

Element integrates Jitsi and Element Call for video and voice conferencing with end-to-end encryption. Threema supports voice and video calls for individuals and groups. Olvid offers secure voice calls inside the app.

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