Microsoft 365 is a comprehensive productivity suite with email, Office apps, and Teams collaboration, while Slack is a specialized messaging and workflow platform. Microsoft 365 offers more integrated tools under one license, whereas Slack excels as a dedicated communication hub that integrates with 2,300+ third-party apps.
Microsoft 365 vs Slack — Side-by-side comparison on A Versus B
Integrated productivity and collaboration suite with Office apps, email, and Teams.
Cloud-based team messaging platform with 2,000+ integrations and 750,000+ active workspaces.
Primary Function. Monthly Cost Per User (Standard Plans). Built-in Email System. Third-Party App Integrations. Cloud Storage Per User. Video Conferencing Participants (Free Plan). Message Search History (Free Plan)
Choose Microsoft 365 if you need a unified productivity ecosystem with email, document creation, video conferencing, and collaboration in one platform, especially for organizations using Windows. Choose Slack if your team prioritizes streamlined messaging, rapid communication, and deep integrations with best-of-breed specialized tools across your existing tech stack.
Microsoft 365: Copilot (premium only) | Slack: N/A
Microsoft 365: Complex enterprise setup | Slack: N/A
Microsoft 365: Full Office suite included | Slack: N/A
Microsoft 365: Comprehensive, moderate | Slack: N/A
Enterprise Security (Intune/Advanced Tools)
Microsoft 365: Industry-leading with Intune E3/E5 | Slack: N/A
Microsoft 365: 1,000GB (1TB) | Slack: N/A
Microsoft 365: Standard in Business plans ($6+/user) | Slack: N/A
Microsoft 365: No (Dynamics 365 separate) | Slack: N/A
Microsoft 365: $69 (Personal) to $100 (Family) | Slack: N/A
Microsoft 365: Windows, macOS, iOS, Android, Web | Slack: N/A
Microsoft 365: Full support | Slack: N/A
Microsoft 365: Yes, native support | Slack: N/A
Microsoft 365: $6 (Business Basic) | Slack: N/A
Microsoft 365: 1,000 GB (OneDrive) | Slack: N/A
Microsoft 365: Unlimited (per subscription) | Slack: N/A
Microsoft 365: ~300 ms for co-authoring sync | Slack: N/A
Microsoft 365: Basic lookup fields in Excel | Slack: N/A
Microsoft 365: Yes (Outlook with 50 GB inbox) | Slack: N/A
Microsoft 365: Yes (full Office suite offline) | Slack: N/A
Microsoft 365: Copilot (separate $20/month add-on) | Slack: N/A
Microsoft 365: Limited to 30 days free trial | Slack: N/A
Microsoft 365: SOC 2 Type II, HIPAA, FedRAMP, ISO 27001, GDPR, CCPA | Slack: N/A
Microsoft 365: 1 hour (Premium Support) | Slack: N/A
Microsoft 365: Yes (unlimited simultaneous users) | Slack: N/A
Microsoft 365: 99% fidelity | Slack: N/A
Microsoft 365: Windows, Mac, iOS, Android, Web | Slack: N/A
Microsoft 365: Copilot, Designer, smart suggestions | Slack: N/A
Microsoft 365: SOC 2, HIPAA, GDPR, FedRAMP | Slack: SOC 2 Type II, ISO 27001, FedRAMP
Microsoft 365: Web-based (minimal local footprint) | Slack: N/A
Microsoft 365: $22 (Microsoft 365 Apps for enterprise) | Slack: N/A
Microsoft 365: 20+ (via Excel integrations) | Slack: N/A
Microsoft 365: Not available | Slack: N/A
Office Suite (Word, Excel, PowerPoint) Included
Microsoft 365: Yes (all included) | Slack: N/A
Microsoft 365: 4-8 (without Power BI) | Slack: N/A
User Learning Curve (1-10 scale, 10=hardest)
Microsoft 365: 2-3 (intuitive Office interface) | Slack: N/A
Microsoft 365: 1,024 GB (1TB) | Slack: N/A
Microsoft 365: 5 devices per subscription | Slack: N/A
Microsoft Office File Format Compatibility
Microsoft 365: 99.9% native support | Slack: N/A
Microsoft 365: 45+ major formats | Slack: N/A
Microsoft 365: iOS, Android, Windows Phone | Slack: N/A
Microsoft 365: Copilot included (most plans) | Slack: N/A
Monthly Cost Per User (Standard Tier, Annual Billing)
Microsoft 365: 1,000 GB (OneDrive) | Slack: 0 GB (integrations only)
Maximum Video Conference Participants (Standard Plan)
Message Search History Retention (Free Plan)
Microsoft 365: N/A | Slack: $87 (billed yearly)
Microsoft 365: N/A | Slack: Up to 2,000 (with paid plan)
Microsoft 365: N/A | Slack: Limited (third-party connectors)
Microsoft 365: N/A | Slack: Slack AI (summarization, search, assisted writing)
Microsoft 365: N/A | Slack: Excellent - optimized search indexing
Microsoft 365: N/A | Slack: $3,600 (Pro plan at $15/user)
Microsoft 365: N/A | Slack: 10,000 most recent
Microsoft 365: N/A | Slack: $8.25 (Pro plan, min 3 users)
Microsoft 365: N/A | Slack: Unlimited (Slack Huddles for video limited to 50 participants)
Microsoft 365: N/A | Slack: Huddles for brief video, limited to 50 participants; requires external tool for full conferencing
Microsoft 365: N/A | Slack: Not native; requires integration with Otter.ai or similar third-party services
Microsoft 365: N/A | Slack: 5 out of 5 (core feature with channels, threads, and history)
Microsoft 365: N/A | Slack: 2 out of 5 (available via integration, not native)
Microsoft 365: N/A | Slack: 30+ (CRM tools, meeting summaries, automation, SlackBot enhancements)
Microsoft 365: N/A | Slack: Cloud-based SaaS only
Microsoft 365: N/A | Slack: Compliant but data on Salesforce servers
Microsoft 365: N/A | Slack: No increases for 33 months
Microsoft 365: N/A | Slack: Unlimited group chats
Microsoft 365: N/A | Slack: Workflow automation, search enhancement
Microsoft 365: N/A | Slack: Not available
Microsoft 365: N/A | Slack: Optimized with threads and archives
Microsoft 365: N/A | Slack: Slack AI (optional on paid plans)
Microsoft 365: N/A | Slack: Limited (requires custom setup)
Microsoft 365: N/A | Slack: Advanced with conditional logic
Microsoft 365: N/A | Slack: Variable by plan
Microsoft 365: N/A | Slack: No, proprietary
Microsoft 365: N/A | Slack: Advanced AI assistant, smart summaries, automation
Microsoft 365: N/A | Slack: Requires 3rd party
Microsoft 365: N/A | Slack: $150 (billed monthly)
Microsoft 365: N/A | Slack: 0 (not native feature)
Microsoft 365: N/A | Slack: 3 participants
Microsoft 365: N/A | Slack: Unlimited (slide deck view only)
Microsoft 365: N/A | Slack: DMs only, Enterprise+ plan
Microsoft 365: N/A | Slack: Slack AI (search, summarization, drafting)
Microsoft 365: N/A | Slack: $12.50 per user/month
Microsoft 365: N/A | Slack: 90 days maximum
Microsoft 365: N/A | Slack: 2000+ integrations
Microsoft 365: N/A | Slack: 15 participants
Microsoft 365: N/A | Slack: Advanced (Workflow Builder, automations)
Microsoft 365: N/A | Slack: 2,300+ integrations
Microsoft 365: N/A | Slack: Unlimited external guests via workspace invite
Microsoft 365: N/A | Slack: $8-12.50 (Pro/Business+)
Microsoft 365: N/A | Slack: 10 years standard
Microsoft 365: N/A | Slack: Channel-based threads (contextual loss in active channels)
Microsoft 365: N/A | Slack: Proprietary (closed-source)
Microsoft 365: N/A | Slack: Native iOS/Android with feature-parity
Microsoft 365: N/A | Slack: Yes (Slack Huddles)
Microsoft 365: N/A | Slack: $412.50/month
Paid Workspaces/Users (Enterprise Adoption)
Microsoft 365: N/A | Slack: 750,000+ paid workspaces
Microsoft 365: N/A | Slack: Proprietary/closed
Microsoft 365: N/A | Slack: $150/month ($1,800/year)
Microsoft 365: N/A | Slack: 2,400+ integrations
Microsoft 365: N/A | Slack: 90-day limited access
Microsoft 365: N/A | Slack: 750,000+ active workspaces
Microsoft 365: N/A | Slack: No (cloud-only)
Microsoft 365: N/A | Slack: Yes (Business+ plan required)
Microsoft 365: N/A | Slack: $12.50/user (Pro plan)
Microsoft 365: N/A | Slack: 10,000 messages (free); unlimited (paid)
Microsoft 365: N/A | Slack: No (requires integrations)
Microsoft 365: N/A | Slack: 50-100ms (instant)
Microsoft 365: N/A | Slack: 5GB (Free), varies by plan
Microsoft 365: N/A | Slack: 0.75 million
Microsoft 365: N/A | Slack: 1 GB shared workspace
Annual Subscription Cost (Pro, 100 users)
Maximum video call participants (free tier)
Microsoft 365: N/A | Slack: 100 participants
Microsoft 365: N/A | Slack: 90 days searchable
Microsoft 365: N/A | Slack: 2,000+ apps (Slack App Directory)
Microsoft 365: N/A | Slack: Cost-effective until ~12 users
Microsoft 365: N/A | Slack: No: messaging-only, requires integrations
Microsoft 365: N/A | Slack: 90 days (Free/Pro), unlimited with Enterprise
Microsoft 365: N/A | Slack: 750+ million messages daily across 750k+ organizations
Monthly Subscription Cost (Pro/Standard)
Microsoft 365: N/A | Slack: All messages indexed instantly
Microsoft 365: N/A | Slack: API-based (basic)
Microsoft 365: N/A | Slack: 100 (workspace)
Maximum Video Conference Participants (Free)
Microsoft 365: N/A | Slack: Limited (typically 3-4)
Microsoft 365: N/A | Slack: 4.6/5 (12,400 reviews)
Microsoft 365: N/A | Slack: Full-text indexed across all messages
Microsoft 365: N/A | Slack: Partial (DMs only, beta feature)
Cost Per User (Annual, Lowest Paid Tier)
Microsoft 365: N/A | Slack: Certified (SOC 2 Type II, GDPR)
Microsoft 365: N/A | Slack: 10,000 (free tier); unlimited (paid)
Microsoft 365: N/A | Slack: Cloud SaaS only
Microsoft 365: N/A | Slack: N/A (proprietary)
How to choose between Microsoft 365 and Slack
Microsoft 365 vs Slack — Structured Comparison Data
Machine-readable comparison dataset for Microsoft 365 vs Slack. Contains 225 attribute comparisons, 5 FAQ pairs.
Microsoft 365 vs Slack — Attribute Category Vocabulary
Taxonomy of attribute categories used to classify comparison data for Microsoft 365 vs Slack.
Slack cannot fully replace Microsoft 365 because it lacks email, document creation (Word/Excel/PowerPoint), and robust video conferencing. However, you can integrate Slack with Google Workspace or Microsoft 365 to use Slack for communication while maintaining your productivity tools. Many companies use both together rather than one replacing the other.
What's the total cost difference when deploying both tools?
For a 100-person company: Microsoft 365 Business Standard costs $1,500/month ($12.50 × 100), while Slack Pro costs $725/month ($7.25 × 100). Combined, Slack + Microsoft 365 = $2,225/month, versus $1,500/month for Microsoft 365 alone. However, if you substitute Slack for Teams, you save the Microsoft 365 cost but lose email, OneDrive, and Office apps.
Which platform is better for remote teams?
For pure communication and quick collaboration, Slack excels with its superior UI, notification handling, and integration flexibility. Microsoft 365 is better if your remote team needs document collaboration, video calls, and email in one platform. Many remote-first companies choose Slack + Google Workspace or Slack + Microsoft 365 together for optimal coverage.
Does Slack have a free plan worth using?
Slack's free plan includes unlimited users, messaging, and basic integrations but limits message history to the last 90 days and restricts file storage. It's suitable for small teams or testing, but enterprise teams quickly outgrow it. Microsoft 365 doesn't offer a true free plan for businesses (Microsoft Teams has a free tier, but no Office apps or email).
How do Teams and Slack messaging compare?
Slack's interface is purpose-built for chat with superior threading, notification customization, and emoji reactions. Teams integrates tighter with Office 365 documents but has weaker notification management and a steeper learning curve. For messaging-focused teams, Slack is generally preferred; for integrated Office workflows, Teams is more efficient.
How to Choose Between Microsoft 365 and Slack
Primary Function: Microsoft 365 has Comprehensive productivity suite (email, docs, spreadsheets, presentations, collaboration), while Slack has Dedicated team messaging and communication platform.
Consider: Monthly Cost Per User (Standard Plans)
Monthly Cost Per User (Standard Plans): Microsoft 365 has $12.50 (Microsoft 365 Business Standard), while Slack has $7.25 (Slack Pro, annual billing).
Built-in Email System: Microsoft 365 has Yes (Outlook included), while Slack has No (third-party integration required).
Third-Party App Integrations: Microsoft 365 has 450+ native integrations, while Slack has 2,300+ available integrations.
Cloud Storage Per User: Microsoft 365 has 1 TB (OneDrive), while Slack has File sharing via third-party apps.
Consider: Video Conferencing Participants (Free Plan)
Video Conferencing Participants (Free Plan): Microsoft 365 has 300 participants (Teams), while Slack has Not available (Slack Calls limited to direct messages).
Consider: Message Search History (Free Plan)
Message Search History (Free Plan): Microsoft 365 has Unlimited search in Outlook, while Slack has Last 90 days only.