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
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.
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.
Video Conferencing Participants (Free Plan)
Microsoft 365 vs Slack — Comparison Data
Structured comparison data for Microsoft 365 vs Slack with 225 attributes.
Enterprise Security (Intune/Advanced Tools)
Office Suite (Word, Excel, PowerPoint) Included
User Learning Curve (1-10 scale, 10=hardest)
Microsoft Office File Format Compatibility
Monthly Cost Per User (Standard Tier, Annual Billing)
Maximum Video Conference Participants (Standard Plan)
Message Search History Retention (Free Plan)
Paid Workspaces/Users (Enterprise Adoption)
Annual Subscription Cost (Pro, 100 users)
Maximum video call participants (free tier)
Monthly Subscription Cost (Pro/Standard)
Maximum Video Conference Participants (Free)
Cost Per User (Annual, Lowest Paid Tier)
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.