Microsoft Teams (Chat) vs Slack

Microsoft Teams (Chat)

The product pages name chat and channels among the solution areas, but we found no public information on threading, message editing history, or search across the archive — and a record I must one day produce to a regulator has to be findable years later, not merely sent.

Slack

Channels and Slack Connect with customer-controlled external boundaries, enterprise and AI-assisted search, and documented history limits (1 year on free, unlimited on paid) give a solid daily surface. But the evidence is silent on threads, message-editing history, and — the part I care about — any export of a conversation in a form a human or a court can read.

Microsoft Teams (Chat)

Encryption of meetings, chats, calls and files is listed as included in the business plans and a free Entra ID identity tier ships in every plan, but the pages state no encryption mechanism, no key custody, no guest-access scoping and nothing on what the vendor itself can read — unverified as a control, in my view.

Slack

Encryption at rest and in transit, SAML SSO, 2FA, SCIM, information barriers and EMM plus customer-controlled posting permissions, DM visibility and Slack Connect gating clear the anchor-5 bar, and the Enterprise Key Management add-on at least puts key handling on paper. But there is no end-to-end encryption anywhere in the evidence, no device verification or session revocation, and no plain statement of what the vendor itself can read.

Microsoft Teams (Chat)

The security and compliance capability I would rely on for hold and discovery is placed in the Microsoft Purview Suite behind a Microsoft 365 E3 requirement, and we found no public information on retention per channel, legal hold, discovery export including edits and deletions, or an audit trail of administrative actions. The privacy statement itself says not all personal data can be accessed or controlled through the provided tools, and it discloses collection of communication metadata and the use of user data to train AI models — both matters a works council will raise.

Slack

Retention configurable at workspace and channel level, plus audit logs and a named legal-hold feature, carry this past rubric level 3. What the evidence never evidences is exactly what I would be subpoenaed for: an eDiscovery export including edits and deletions, proof that retention deletions are actually executed, and any organisation-wide switch for activity analytics — named bullets on a pricing page are not a discovery process.

Microsoft Teams (Chat)

Personal data may be stored and processed in the user's region, the United States and any other jurisdiction where Microsoft, its affiliates, subsidiaries or service providers operate, and we found no public information on self-hosting, a dedicated-instance option, or a documented full-archive export. The only custody transition the captured pages document is deletion of all data on subscription cancellation — a destruction event, not a handover of the record.

Slack

Nothing in the evidence offers the customer custody: no self-hosting, no private instance, no open source, and — decisive for an exit — no documented export of any kind. The EKM add-on and Germany hosting from Business+ are controls over Slack's cloud, not an alternative to it, so this sits at the bottom of the scale nudged up only by key custody.

Microsoft Teams (Chat)

Over 250 integrated business apps and custom chatbot creation through Copilot Studio are publicly stated, with agents requiring a Copilot licence or a consumption-based Azure subscription; we found no public information on a documented API, webhooks, or rate limits a builder could plan against.

Slack

A real ecosystem is implied — named integrations, SCIM provisioning, SAML SSO — and I welcome the workspace-level power to allow or restrict third-party services. But the evidence documents no REST API, no webhooks, no bot framework and no rate limits, so whether this is buildable without a partner agreement is unproven from evidence.

Microsoft Teams (Chat)

The vendor is a United States corporation whose privacy statement allows personal data to be stored and processed in the user's region, the United States and any jurisdiction where Microsoft or its affiliates, subsidiaries or service providers have facilities, with transfers resting on the EU-US data privacy framework; we found no public information on EU data residency as standard, an EU contracting entity, or a named subprocessor list. An archive I must defend is not under my client's jurisdiction here.

Slack

The contracting entity is Salesforce, Inc. of San Francisco and no subprocessor chain is named, while the AI stack runs in Slack's own AWS private cloud with no region stated and a US LLM provider sits in the integration list. Germany data residency exists but is purchasable only from Business+ upward — partial residency on top of a non-EU entity is precisely the anchor-3 pattern.

Microsoft Teams (Chat)

The public pages price the add-ons exactly — Teams Premium at 8,70 € per user per month and Microsoft 365 Copilot Business at 18,20 € per user per month, annual billing, VAT excluded — and state storage and user limits, but we found no public per-user price for the core plans themselves, and the compliance tooling I need for retention and discovery is stated to require Microsoft 365 E3, for which no public price is captured. The annual invoice for a compliant deployment is not computable from these pages alone.

Slack

The pricing page does place compliance features per plan — DLP across plans, Germany residency from Business+, audit logs and legal hold listed, VAT-compliant invoices downloadable. But Enterprise Key Management is an unpriced add-on, the evidence shows no per-user figures or minimum term, and I cannot tell which tier legal hold actually sits in, so the annual invoice for my compliance setup is not computable from what is captured.