The European alternatives to Slack fall into two groups: services a European company hosts for you, such as Enclessa, Wire, Threema Work and Stackfield, and software you run on servers of your choosing, such as Element on Matrix, Nextcloud Talk, Rocket.Chat and Mattermost. They differ most on end-to-end encryption: Wire and Threema encrypt everything, Enclessa encrypts direct messages with MLS and keeps channels searchable, Element encrypts private conversations by default, and the rest encrypt some conversations or none.
Who runs it, where, and what is end-to-end encrypted
Source of every claim
Each vendor’s own public pages
Checked
September 2026
Prices
Not quoted — they change faster than a page does
Written by
Enclessa, which is on the list and not neutral
The alternatives at a glance
Three questions decide most shortlists: whose company it is, who operates the servers, and which conversations the operator cannot read.
European and privacy-focused Slack alternatives, compared on vendor, hosting and encryption
European and privacy-focused Slack alternatives, compared on vendor, hosting and encryption
Company based in
How it is run
End-to-end encryption
Enclessa
Germany
Hosted in the EU by the vendor only
Direct messages (MLS); channels readable by the server by design
Element (Matrix)
United Kingdom
Self-hosted, or managed hosting by Element
On by default in direct messages and private rooms (Olm and Megolm)
Wire
Switzerland
Vendor cloud, on-premises or hybrid
Everything, always on (MLS)
Threema Work
Switzerland
Hosted in Switzerland, or Threema OnPrem
Everything
Nextcloud Talk
Germany
Self-hosted, as part of Nextcloud
Calls; chat is stored on your server
Stackfield
Germany
Hosted in Germany by the vendor
Optional, per room
Rocket.Chat
Brazil
Self-hosted, or vendor cloud
Optional; an administrator enables it
Mattermost
United States
Self-hosted first, with a cloud offering
Not offered as a platform feature
Statements about other products come from their own public pages and describe the position as last checked in September 2026. Vendors change what they offer; check the current documentation before deciding on the strength of this page.
The options, one by one
What each product is good at, how it is run, what it encrypts, and the thing to weigh before choosing it.
Enclessa
Company based in
Germany
Good at
Chat, video calls, task boards, time tracking and people records in one hosted workspace, with direct messages the operator cannot read.
Hosting
Operated by Quavon UG (haftungsbeschränkt) in one European Union region. Not open source and not self-hostable; Enterprise buys a dedicated deployment that we still operate.
Encryption
Direct and group direct messages are end-to-end encrypted with MLS (RFC 9420) through OpenMLS. Channels are managed: the server can read them so search, retention and export work, and every room shows which kind it is.
Weigh this
Open beta. No certifications, no external security audit yet, one hosting region and no mobile apps yet.
An open, federated standard: organisations run their own Matrix servers and can still talk to each other. Matrix underpins several European public-sector messengers.
Hosting
Open-source servers and clients you can run yourself; Element, the company led by the creators of Matrix, also sells a fully managed hosting service.
Encryption
Direct messages and private rooms are end-to-end encrypted by default, using the Olm and Megolm algorithms defined in the Matrix specification.
Weigh this
Running a federated server well is real operational work, and key backup and device verification ask something of every user.
Messaging, calls and file sharing for organisations that need every conversation end-to-end encrypted, with no exceptions to explain.
Hosting
Wire Swiss GmbH offers its cloud service as well as on-premises and hybrid deployments.
Encryption
Wire states that end-to-end encryption is always on and cannot be disabled, for messages, calls and files, and that its platform is secured by MLS.
Weigh this
When the server can read nothing, server-side search, retention and compliance export of content work differently from a workspace whose channels the server can read.
A secure business messenger managed centrally by the company, for teams that mostly communicate from their phones.
Hosting
Threema runs its services on its own servers in Switzerland; Threema OnPrem is the self-hosted version of Threema Work.
Encryption
Threema describes consistent end-to-end encryption, with encryption and decryption happening on the device, so that it cannot read message content itself.
Weigh this
A messenger first: it is not trying to be a channel-based workspace with boards or time tracking. Switzerland is outside the EU, with an EU adequacy decision.
Teams that already run Nextcloud for files and want chat and video calls beside them, on a server they control.
Hosting
Open-source software you install on your own server, or buy from a provider that hosts Nextcloud for you.
Encryption
Nextcloud documents end-to-end encrypted calls. Chat messages are kept on the Nextcloud server you operate; check its documentation for the current position.
Weigh this
You operate it, including the additional backend components that larger calls need.
Open-source team chat you can run on your own servers, with customer-facing omnichannel messaging and a wide set of integrations.
Hosting
Self-hosted on infrastructure you choose — in Europe if you choose Europe — or used as the vendor’s cloud service.
Encryption
End-to-end encryption for direct messages and private rooms is a workspace setting an administrator turns on; encrypted messages do not appear in search.
Weigh this
The company is not European. What makes it European is where you run it, which makes you the operator.
Engineering and operations teams that need to run chat themselves, with an established plugin ecosystem and mature single sign-on in commercial editions.
Hosting
An open-source core with commercially licensed editions, designed first for self-hosting, with a cloud service alongside.
Encryption
Messages are encrypted in transit to the server you run, which can read them; end-to-end encryption is not a platform feature.
Weigh this
A US vendor. Keeping the data in Europe is a property of your deployment, not of the product.
Three different things get called European, and they are worth separating. The first is the company: a vendor established in the EU, or in a country with an EU adequacy decision such as Switzerland or the United Kingdom, is subject to European law without a parent elsewhere. The second is where the data sits, which for self-hosted software is your decision rather than the vendor’s. The third is who operates the servers day to day, because an operator can read whatever is not end-to-end encrypted. Enclessa, Stackfield and Nextcloud are German companies, Wire and Threema are Swiss, and Element is British. Rocket.Chat and Mattermost are built outside Europe and become European only when you run them on European servers yourself. For a data protection assessment, write down which of the three you actually need before comparing features, because the shortlists they produce are different.
Which Slack alternatives are end-to-end encrypted?
Slack itself does not offer end-to-end encryption; its top tier offers customer-managed keys, which is a different control. Among the alternatives the answer ranges from everything to nothing. Wire and Threema Work encrypt every conversation, and Wire states that its platform is secured by MLS. Element encrypts direct messages and private rooms by default with Megolm, the Matrix group algorithm. Enclessa encrypts direct and group direct messages with MLS, RFC 9420, and deliberately leaves channels readable by the server so that search, retention and export work, showing each room’s mode to its members. Stackfield and Rocket.Chat offer encryption as an option, per room or per workspace setting. Nextcloud documents encrypted calls, and Mattermost does not offer end-to-end encryption as a platform feature. More encryption is not automatically better: whatever the server cannot read, it cannot search, retain or export for you either.
Should you choose a hosted or a self-hosted alternative?
Self-hosting gives you control of where the data sits and when the software changes, and it makes you the operator: patching, backups, monitoring, scaling calls and answering the security questionnaire are your team’s work from then on. It suits organisations that already run infrastructure and have a reason to keep it in-house, which is why Element, Nextcloud Talk, Rocket.Chat and Mattermost are strong there. A hosted service moves that work to the vendor, and the question becomes whether you trust how the vendor runs it and what the vendor can read. Enclessa is hosted only: Quavon runs every organisation, in one EU region, and there is no self-hosted licence. Wire and Threema offer both. If a requirement says the software must run on your own servers, Enclessa is ruled out, and this page should save you the evaluation.
When is Slack still the better choice?
Slack remains the better choice when your process runs on its third-party app directory, when you rely on shared channels with other companies that are already on Slack, or when the interaction design your team knows matters more than where the data is processed. None of the alternatives here matches Slack’s ecosystem, and pretending otherwise would make this page an advertisement. It is also worth checking what Slack offers for data residency on the plan you would buy, because for some buyers that answers the question without a migration. The case for a European alternative is strongest when the constraint cannot move: a data protection requirement that the operator must not read certain conversations, a procurement rule about the vendor’s jurisdiction, or a board that wants the collaboration tool out of a non-European parent company’s reach. If none of these applies to you, switching tools is a cost with little return.
How was this comparison put together?
Each product was checked against its vendor’s own public pages in September 2026: where the company is based, how the software is deployed, and what the vendor says is end-to-end encrypted. Facts that could not be confirmed there were left out rather than guessed, and no prices, user numbers or certifications of other vendors are quoted, because those change faster than a page is revised and are easy to get wrong. The list covers the products European teams most often weigh against Slack; it is not exhaustive, and leaving a product out says nothing about it. Enclessa wrote this page and is one of the eight products on it, so read its entry with that in mind and check the others at the source through the links provided. If a statement about your product is out of date, the contact page reaches the people who can correct it.
Yes, several. Wire and Threema Work, both Swiss, encrypt every conversation end to end. Element on Matrix encrypts direct messages and private rooms by default. Enclessa, hosted in the EU by a German company, encrypts direct and group direct messages with MLS and keeps channels readable by the server so search and export work. Stackfield offers encryption per room.
Element and the Matrix server software, Nextcloud Talk, Rocket.Chat and Mattermost are built to be self-hosted, and Wire and Threema offer on-premises editions. Enclessa and Stackfield are hosted services only.
No. Enclessa is a hosted service operated by Quavon UG in the European Union. It is not open source and there is no self-hosted licence; the Enterprise plan buys a dedicated deployment that Quavon still operates. Its architecture, data model, OpenAPI surface and encryption design are published for review.
No. Slack offers Enterprise Key Management on its top tier, which lets a customer control the encryption keys, but the service still processes message content in plaintext. That is a real control and a different thing from end-to-end encryption.
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