What can replace Slack.
4 European products that cover Slack fully or in part. None of them is a clone — where something is missing, it says so.
4 entries
Nextcloud TalkDE
Chat and video meetings inside the same system as files and calendar — for anyone already running Nextcloud, the cheapest step away from Teams.
EU / EEASolidEffort: SmallOpen sourceSelf-hostableCatchLarge meetings need the separate high-performance backend. Without it, things get sticky past a dozen participants.
nextcloud.com/talk Replaces: Microsoft Teams · Slack · Zoom
Threema WorkCH
A messenger with no phone number and no address-book upload, with a business variant and a server you can run yourself.
SwitzerlandProvenEffort: SmallOpen sourceSelf-hostablethreema.ch Replaces: WhatsApp · Slack
WireCH
An end-to-end encrypted messenger with conferencing, used by public bodies, with a server edition you can run yourself.
SwitzerlandSolidEffort: MediumOpen sourceSelf-hostablewire.com Replaces: Microsoft Teams · Slack · WhatsApp
Element / MatrixGB
Encrypted chat on the open Matrix protocol — the basis of Germany's BwMessenger, the French administration's messenger and many universities.
United KingdomProvenEffort: MediumOpen sourceSelf-hostableCatchElement Software is based in London. Self-hosting makes that irrelevant; if you buy Element Cloud, pin the instance location in the contract.
element.io Replaces: Microsoft Teams · Slack · WhatsApp
Every field, filter and catch lives in the full directory. Not a recommendation and not a review. A list with evidence, so you can draw up a shortlist. Ownership and headquarters change — verify whatever matters to you before you sign.
Data as of August 2026