Microsoft Teams (Chat) vs Slack

Microsoft Teams (Chat)

The captured pages name chat and channels as a core solution area, but we found no public information on threading, mentions, search across history, or export of a conversation in a form a person can read. For a works council, a chat that records who spoke to whom at what hour is a record, and none of the record-handling surface beyond the channel name itself is evidenced here.

Slack

Channels, Slack Connect with 4M external users, file sharing and AI search across stored company knowledge are evidenced, with documented history limits (free: 1 year, paid: unlimited). But the evidence says nothing about threads, message edit history, or exporting a conversation a human can read — for a chat log to be a record, I need that archive story, not just search.

Microsoft Teams (Chat)

Encryption of meetings, chats, calls and files is listed as included in the business plans, but the captured pages do not document the mechanism, key custody or a per-channel role model. A free Microsoft Entra ID layer in every plan is the extent of the access evidence; we found no public information on guest handling, session revocation, device verification, or a plain statement of what the vendor itself can read.

Slack

Encryption at rest and in transit with vendor-held keys by default; Enterprise Key Management is only a paid add-on, which is the right direction but not first-class. SSO, 2FA, information barriers and admin control over DM visibility and external connections are documented, but there is no end-to-end mode and no plain statement of what Slack itself can read.

Microsoft Teams (Chat)

Retention, deletion and destruction are pointed to somewhere in Microsoft 365 and cancellation deletes associated data, but compliance and data security sit in a separately licensed Purview suite gated on an E3 plan. The captured pages confirm that time, date and the users involved in communication are recorded, while we found no public information on user-controlled presence, an administrative audit trail, discovery export, or activity analytics that can be switched off organisation-wide — exactly the points a works agreement turns on.

Slack

Retention is configurable at workspace and channel level, and legal hold, audit logs and native DLP exist — but the evidence is silent on discovery export in any format, on whether deletion is evidenced, on user-controlled presence, and on switching analytics off organisation-wide. A works agreement cannot rest on half of rubric level 5; those absences are information.

Microsoft Teams (Chat)

Everything captured is a cloud subscription with automatic renewal; we found no public information on a self-hosted or source-available edition, federation, or a documented organisational export of chat and files. The only data-out path shown is the individual privacy dashboard, and the privacy statement itself says not all personal data can be retrieved or controlled through those tools — so the archive stays with the vendor.

Slack

Cloud-only and proprietary: no self-hosting, no open source, no federation, and no documented full export anywhere in the evidence — not even the partial one rubric level 0 would still allow scoring. Germany data location from Business+ and LLMs in Slack's own AWS cloud are residency, not custody; the archive belongs to Salesforce either way.

Microsoft Teams (Chat)

Over 250 integrated business apps are advertised and a custom chatbot builder via Copilot Studio is included even in the lower business plans, with Entra ID providing the identity layer. But we found no public information on a documented REST API, webhooks, event subscriptions, rate limits or a sandbox — the machinery a works council would want to audit before bots read our channels.

Slack

SSO, SCIM provisioning, a workflow builder usable with or without code, and named integrations (Google Drive, ChatGPT, Asana, Workday) with workspace-level allow/restrict control are all evidenced. But the evidence captures no documented API, no webhook model, no rate limits or sandbox — I cannot credit a platform on integration logos alone.

Microsoft Teams (Chat)

Microsoft is a United States company, and the privacy statement reserves the right to store and process personal data in the user's region, in the United States, and in any jurisdiction where Microsoft or its service providers operate, relying on the EU-US data privacy framework for transfers. The contracting entity's jurisdiction and the subprocessor list are not confirmed on the vendor's own captured pages, and we found no public information on EU-standard hosting or European custody of the archive.

Slack

Germany data residency exists but only from Business+ upward, while the contracting entity is Salesforce, Inc. of San Francisco and the subprocessor chain is unnamed — exactly the rubric level 3 situation. The LLMs run in Slack's own AWS private cloud and ChatGPT is a showcased integration with no legal basis or safeguard stated for that reach.

Microsoft Teams (Chat)

Per-user add-on prices are public with billing period, VAT treatment, a seven-day cancellation right and free-trial auto-conversion all stated, which is more than a sales conversation. But compliance and data security are routed to a Purview suite requiring a Microsoft 365 E3 plan, and we found no public price for that plan on the captured pages, nor per-user prices for the base plans themselves — so a buyer cannot compute the annual invoice for the retention and compliance features they actually need.

Slack

Tier boundaries are genuinely public — which plan gets unlimited history, legal hold, audit logs, SCIM, Germany hosting and which SLA — and VAT-compliant invoices are downloadable. But not a single per-user price figure appears in the captured pricing pages, and Enterprise Key Management is an unpriced add-on, so the annual invoice for our headcount is not computable from what is published here.