Slack and Microsoft Teams both give you channels, direct messages, meetings and apps in one place. The practical difference for most mid-market buyers is the surrounding stack. Teams is part of Microsoft 365, so it shares identity, files and compliance tools with the rest of that suite. Slack is a standalone platform that connects to many other tools, such as Salesforce, Jira and Google Drive.
If your organization already runs Microsoft 365 and needs a business phone system, Teams is usually the simpler fit. If your teams work heavily across many SaaS tools or with outside partners in shared channels, Slack deserves a serious look. Both offer data residency and customer-managed encryption keys, but at different plan levels.
OPS resells and deploys both Slack and Microsoft 365, so this comparison does not favor either one. The right choice follows your requirements. Product details below come from Slack and Microsoft documentation, checked on October 28, 2026.
Slack and Teams at a glance
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| Area | Slack | Microsoft Teams |
|---|---|---|
| Structure | Channels and DMs, grouped into workspaces or an Enterprise organization | Teams with channels, plus one-to-one and group chats |
| Live meetings | Huddles, up to 50 people on paid plans | Meetings up to 300 people on Business plans, 1,000 on Enterprise plans |
| Business phone | Not part of the plan features we reviewed | Teams Phone, an add-on or part of some suites |
| External work | Slack Connect channels, up to 250 organizations | Shared channels through B2B direct connect, plus guest access |
| Data residency | Business+ and Enterprise plans | Product Terms commitments, plus Advanced Data Residency and Multi-Geo add-ons |
| Customer-managed keys | Enterprise Key Management add-on | Customer Key |
How messaging is organized
Slack is built around channels. Slack's plan comparison lists canvases, lists, customizable sidebar sections and audio and video clips alongside messaging. Larger customers run an Enterprise organization, where admins manage settings, members, channels and apps for every workspace from one admin dashboard.
In Teams, a team contains channels, and people also message in private and group chats. Microsoft explains that every team is backed by a Microsoft 365 group with its own SharePoint site and Exchange mailbox. That link is the main reason Teams fits well when your files already live in SharePoint and OneDrive.
For work with other companies, Slack Connect lets up to 250 organizations share one channel on paid plans. Teams offers shared channels with people in other Microsoft 365 organizations through Microsoft Entra B2B direct connect. Both organizations must configure cross-tenant access before this works.
Meetings and calling
Slack's meeting tool is the huddle. According to Slack's huddles guide, paid plans allow up to 50 participants, with up to 25 on video at a time, and the Free plan allows two. Huddle notes with summaries are included on paid plans.
Teams meetings are larger. Microsoft's Teams limits allow up to 300 people with Microsoft 365 Business plans and up to 1,000 with Enterprise plans such as Microsoft 365 E3 and E5. Enterprise plans can add view-only attendees up to a total of 11,000.
For telephony, Teams Phone Standard adds cloud voicemail, call forwarding and transfer, auto attendants, call queues and caller ID. You connect it to the public phone network through a Microsoft Calling Plan or another connectivity option. Microsoft 365 E5 includes the phone system capability. Slack's plan pages do not list a business phone system, so if users need their own phone numbers on Slack, plan a separate telephony service.
Apps and integrations
Slack's pricing page lists more than 2,600 apps in the Slack App Directory. The Free plan is limited to 10 integrations, and paid plans add Workflow Builder, custom workflow steps and the option to deploy apps to Slack's infrastructure.
In Teams, admins control every app, including those published to the Teams store. They allow or block each app in the Teams admin center and can use app centric management to make an app available to specific users or groups.
Admin, security and compliance
Slack places most compliance controls on its top plans. Slack's plan comparison shows:
- Custom retention policies from the Pro plan.
- Data residency and full message exports from Business+.
- Native data loss prevention, information barriers, legal holds, the Discovery API, audit logs, Enterprise Mobility Management and custom roles on Enterprise+.
Enterprise customers can send events to a security monitoring tool through the Audit Logs API.
Teams uses Microsoft Purview for compliance. Microsoft's Teams security and compliance overview lists communication compliance, retention policies, data loss prevention, eDiscovery and legal hold, audit log search, information barriers and mobile app management with Intune. Which of these you can use depends on your Microsoft 365 suite, so map each requirement to your actual licenses.
Data residency and encryption keys
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| Requirement | Slack | Microsoft Teams |
|---|---|---|
| Choose a storage region | Data residency on Business+ and Enterprise plans, one region per customer | Advanced Data Residency add-on for eligible countries |
| Example regions | London, Frankfurt, Paris, Zurich, Montreal, Singapore, Sydney, Tokyo | United Kingdom, Canada, Switzerland, United Arab Emirates, Australia and others |
| Users in several regions | One region per customer | Multi-Geo add-on stores chat data in each user's assigned location |
| Your own keys | Enterprise Key Management add-on, keys in Amazon's Key Management Service | Customer Key, root keys in Azure Key Vault |
Check the fine print on both sides. Slack stores messages, files and the search index in the chosen region, but member profiles and membership data may sit elsewhere, and data created before you enable residency stays in the US unless you request a migration. Slack's Enterprise Key Management is an add-on for the Enterprise Grid and Enterprise+ plans.
Microsoft requires Advanced Data Residency licenses for 100% of paid licenses in the tenant, and the European Union is not available as a single Advanced Data Residency geography. Multi-Geo requires units for more than 5% of eligible seats. Customer Key covers Teams chat messages and recordings held in Teams storage, while Teams files saved in SharePoint or OneDrive need a separate SharePoint encryption policy.
Licensing
Microsoft includes Teams in Microsoft 365 Business Basic, Standard and Premium, and also sells versions of its suites without Teams. Microsoft states that Microsoft 365 E3 and E5 and Office 365 E1, E3 and E5 suites that include Teams are no longer available to new customers. Microsoft's licensing tables show new customers pairing a no-Teams suite with a Teams Enterprise license. Our guide to Microsoft 365 price changes in 2026 lists the published prices for suites with and without Teams.
Slack sells Free, Pro, Business+ and Enterprise+ plans, with Enterprise pricing through its sales team. Slack's pricing changes with promotions and billing terms, so take a dated quote from the Slack pricing page or your reseller rather than relying on a figure in an article.
When each fits
Teams usually fits when:
- You already license Microsoft 365 and store files in SharePoint and OneDrive.
- You need a business phone system or meetings above 50 people.
- Your compliance team already works in Microsoft Purview.
Slack usually fits when:
- Your people work across many SaaS tools and want deep app and workflow automation.
- You collaborate daily with customers, agencies or suppliers in shared channels.
- You run Google Workspace or a mixed stack and do not want chat tied to one suite.
If neither fits because data must stay on infrastructure you control, consider a self-hosted platform.
Decision checklist
- Current stack. List your email, file storage and identity provider, and where each sits today.
- Meeting and phone needs. Count users who need phone numbers and the size of your largest regular meetings.
- External collaboration. Record which partners you work with and which platform they use.
- Compliance controls. Map retention, legal hold, data loss prevention and audit needs to a specific plan on each side.
- Data residency. Name the country or region your data must stay in and check it against both vendors' lists.
- Key management. Decide whether you must hold your own encryption keys, and who in your team would manage them.
- Total cost. Compare full licensing, including add-ons such as Teams Phone, data residency and key management, plus migration and training.
- Exit plan. Confirm how you would export messages and files if you change platform later.
Common questions
Is Microsoft Teams included in Microsoft 365?
Teams is included in Microsoft 365 Business Basic, Standard and Premium. Microsoft no longer sells its E-series suites with Teams to new customers, who can pair a suite without Teams with a Teams Enterprise license.
Can Slack keep data in the UK or EU?
Yes, on Business+ and Enterprise plans. Slack lists London, Frankfurt, Paris, Stockholm and Zurich among its data residency regions, with one region per customer.
How many people can join a Slack huddle?
Up to 50 on paid plans, with up to 25 sharing video at a time. The Free plan allows two participants.
Can I use my own encryption keys?
Yes, on both. Slack offers Enterprise Key Management as an add-on for Enterprise Grid and Enterprise+, and Microsoft offers Customer Key, which covers Teams chat data.
Which is better for working with other companies?
Both support it. Slack Connect channels can include up to 250 organizations. Teams shared channels need both organizations to enable B2B direct connect.
Compare your options with OPS
OPS resells, deploys and supports both platforms through its Collaboration & Workplace practice. See the Slack and Microsoft 365 service pages, or Mattermost if you need a self-hosted option. Bring your requirements, and OPS can map them to the right plan.
Sources
- Slack, Slack plans and features. Checked October 28, 2026.
- Slack, Pricing. Checked October 28, 2026.
- Slack, Data residency for Slack. Checked October 28, 2026.
- Slack, Slack Enterprise Key Management. Checked October 28, 2026.
- Slack, Use huddles in Slack. Checked October 28, 2026.
- Slack, Use Slack Connect to work with other companies in channels. Checked October 28, 2026.
- Slack, Guide to the Slack admin dashboard. Checked October 28, 2026.
- Slack, Audit logs in Slack. Checked October 28, 2026.
- Microsoft, Limits and specifications for Microsoft Teams. Checked October 28, 2026.
- Microsoft, Meetings and events feature comparison. Checked October 28, 2026.
- Microsoft, Microsoft Teams add-on licenses. Checked October 28, 2026.
- Microsoft, Teams Phone licensing. Checked October 28, 2026.
- Microsoft, Shared channels in Microsoft Teams. Checked October 28, 2026.
- Microsoft, Collaborate with external participants in a shared channel. Checked October 28, 2026.
- Microsoft, Manage your apps in the Microsoft Teams admin center. Checked October 28, 2026.
- Microsoft, App centric management to manage user access to Teams apps. Checked October 28, 2026.
- Microsoft, Overview of security and compliance in Microsoft Teams. Checked October 28, 2026.
- Microsoft, Advanced Data Residency overview and requirements. Checked October 28, 2026.
- Microsoft, Data residency for Microsoft Teams. Checked October 28, 2026.
- Microsoft, Overview of Customer Key. Checked October 28, 2026.