Slack vs Microsoft Teams:
channel conversations, Microsoft integration and retention.
Compare Slack and Microsoft Teams for channel conversations, Microsoft integration and retention, with practical buying briefs and plan boundaries.
Start with the work.
Then choose the package.
Slack is a useful shortlist for conversation organised around channels and a broad mix of connected apps. Microsoft Teams is a useful shortlist when communication should sit within a Microsoft 365 environment. Choose using actual discussion, guest-access and retention requirements; the free products and paid business packages are not equivalent records systems.
Seven differences that change the shortlist
| Buying question | Slack | Microsoft Teams |
|---|---|---|
| Conversation structure | Channels, direct messages and connected app activity | Chat and business team collaboration |
| Existing environment | Connects discussion with a mixed business app stack | Connects communication with Microsoft 365 services |
| Short calls | Slack huddles; Free limits them to one-to-one | Online meetings; edition determines meeting scope |
| External work | Slack Connect has plan-dependent collaboration | Guest and external collaboration need business configuration review |
| Free history | 90-day searchable history; older-than-one-year data deleted | Free is distinct from the managed business service |
| Business purchase | Slack plans with per-user subscriptions | Standalone Teams options or selected Microsoft 365 packages |
| Advanced tools | AI and security entitlements vary by Slack plan | Phone, advanced meetings and Copilot require licence review |
Four worked buying briefs
These are hypothetical scenarios with explicit assumptions. They do not establish equal capabilities, measured usability or a negotiated price.
| Buying brief | Slack | Microsoft Teams |
|---|---|---|
| A product team works across several apps | Create a sample project channel and route only essential app events. | Create the equivalent discussion space and connect the required tools. |
| A Microsoft-centred company wants one collaboration home | List separate access and document-sharing arrangements. | Trace the proposed workflow through the organisation’s Microsoft accounts. |
| An agency works with clients every day | Review the intended Slack Connect arrangement and plan. | Review the intended external or guest arrangement and tenant settings. |
| A team relies on historical decisions | Compare required retention with Free and paid history policies. | Specify retention and discovery needs for the actual business licence. |
A product team works across several apps
Where should decisions and notifications meet?
Slack: Create a sample project channel and route only essential app events.
Microsoft Teams: Create the equivalent discussion space and connect the required tools.
Ask a colleague to find a decision one week later. Count irrelevant notifications and missing context rather than relying on an integration count.
A Microsoft-centred company wants one collaboration home
Which work can be completed without duplicate accounts?
Slack: List separate access and document-sharing arrangements.
Microsoft Teams: Trace the proposed workflow through the organisation’s Microsoft accounts.
Price overlap with existing subscriptions, and confirm whether Teams is actually included.
An agency works with clients every day
How will a client join, leave and access project history?
Slack: Review the intended Slack Connect arrangement and plan.
Microsoft Teams: Review the intended external or guest arrangement and tenant settings.
Test with an authorised external account, including file access after the engagement closes.
A team relies on historical decisions
What must remain retrievable?
Slack: Compare required retention with Free and paid history policies.
Microsoft Teams: Specify retention and discovery needs for the actual business licence.
Do not use a free chat archive as the only copy of a contract approval or compliance record.
Design the conversation structure first
A migration of every email thread into a channel can reproduce the same confusion in a new interface. Define where announcements, project decisions and quick questions belong, and decide who closes outdated spaces. Give each active project a clear owner and a short description of what should be discussed there. Establish a small set of notification rules so the pilot tests a usable working pattern rather than an unrestricted stream of alerts.
Use the same fictional project in both candidates: a launch brief, one changed deadline and a client question. Ask a participant who missed the discussion to locate the latest decision and identify who agreed to it. Include a file permission issue and an external collaborator. These proposed tasks reveal the organisation’s needs without asserting that one vendor has a faster search or a universally simpler interface.
Treat history and access as buying requirements
Before selecting a free plan, list the conversations that staff need to retrieve six or twelve months later. Keep a separate system of record for binding approvals and controlled documents. Slack’s free-history policy is a concrete boundary to plan around; Teams Free should likewise not be substituted for an organisation’s required business controls. Ask administrators to explain what happens when someone leaves and when a client loses access.
Build the quote around employees, external parties and administrative roles. Include the existing suite cost only where the proposed package actually includes the relevant communication licence, and identify separately priced telephone or AI services. A pilot is complete when an administrator can describe onboarding, retention and offboarding, as well as when employees can send messages successfully.
Questions before you choose
Can Slack Free keep an unlimited searchable history?
No. Slack Free provides a 90-day searchable window, and data older than one year is deleted under its published policy.
Is Teams automatically free for every Microsoft 365 customer?
The relevant question is whether Teams is included in the specific subscription. Microsoft offers packages with and without Teams, as well as separate options.
Can we compare the free editions for a business rollout?
They can be useful for a small evaluation, but business retention, external access and administration requirements must be checked against the paid package being considered.
Which has better AI?
This comparison does not measure answer quality. Define an approved summarisation or search task, confirm entitlement and evaluate the output before adding AI to the purchase decision.
Turn the comparison into your own evaluation
Use the same criteria and priorities for both products, keep unknowns unassessed and record the plan and evidence behind your ratings.
Build a Slack vs Microsoft Teams scorecard →Keep the assumptions with the figures
Use the date, billing cycle, units and limits with each example. Check current account terms before purchasing. Unverified prices and model costs stay unpriced.
Download the buying examples as JSON ↓Share the comparison
Use these examples when discussing the shortlist with your team.