Does Slack offer a free version for history retention?

Slack offers a free plan that includes access to a limited history of messages and files. Organizations requiring long-term, searchable history should review the specific retention limits associated with their chosen paid plan.

Is Microsoft Teams included in Microsoft 365?

Microsoft Teams is a component of many Microsoft 365 business subscriptions. Organizations should verify their specific license agreement to confirm inclusion and feature availability.

How do these tools differ in their approach to external collaboration?

Slack provides Slack Connect for working with external partners, while Microsoft Teams utilizes Guest Access. The choice depends on the organization's existing security and identity management policies.

Slack vs. Microsoft Teams: Strategic Communication Selection

Question: Should a team use 'Slack' or 'Microsoft Teams' for internal communication, considering the cost of message history retention and integration with existing productivity suites?

Prepared by the ChoiceScore Research Desk · Editor-approved for the curated library · Reviewed July 31, 2026

It depends Choice Score: 75/100

Direct answer

Organizations currently standardized on the Microsoft ecosystem may find Microsoft Teams to be a logical extension of their existing productivity suite. Conversely, teams operating in heterogeneous environments that require extensive third-party integrations, custom workflow automation, or specialized agentic tools may prioritize Slack. The choice hinges on whether the organization values the consolidation of services within a single vendor framework or the flexibility of a modular, integration-first communication platform.

Summary

Selecting between Slack and Microsoft Teams requires balancing existing infrastructure investments against specific workflow requirements. Microsoft Teams is a component of the broader Microsoft product ecosystem. Slack functions as an AI-powered work platform that emphasizes modular integrations, workflow automation, and agentic capabilities. The decision-making process should prioritize whether the organization's current software stack provides a native communication solution or if the operational benefits of a specialized platform justify the incremental cost of a separate subscription. This report provides an analytical framework for comparing these tools, utilizing user-adjustable assumptions to model Total Cost of Ownership (TCO).

Choice Score breakdown

Microsoft Teams Ecosystem Integration 95/100 — Native integration with the broader Microsoft suite.
Slack Workflow and Integration Ecosystem 90/100 — Highly modular platform designed for custom integrations and agentic workflows.
Cost Efficiency (M365-Standardized) 85/100 — Teams is a component of many existing Microsoft 365 business subscriptions.

Best for / Not best for

Best for

Teams already using Microsoft 365
Organizations with strict IT-managed compliance requirements
Agile teams needing deep, custom integrations with non-Microsoft tools
Teams prioritizing high-speed, intuitive chat interfaces

Not best for

Budget-constrained teams that do not already have Microsoft 365
Teams that find the Microsoft interface overly complex
Organizations requiring absolute lowest cost per user without considering integration value

Scenarios

The Microsoft-Centric Enterprise (60% likely)
The organization is fully committed to the Microsoft ecosystem for productivity and cloud storage. This probability is an illustrative, user-adjustable scenario weight, not an empirical forecast.
The Agile Multi-Tool Environment (25% likely)
The organization utilizes a diverse stack of third-party tools and prioritizes specialized workflow automation. This probability is an illustrative, user-adjustable scenario weight, not an empirical forecast.
The Hybrid Cost-Optimizer (15% likely)
The organization uses M365 for core office tasks but selects Slack for its specific chat interface and automation capabilities. This probability is an illustrative, user-adjustable scenario weight, not an empirical forecast.

Calculations

Metric	Result	Formula
Illustrative Annual M365 Communication Cost	150 USD/user/year	monthly_m365_cost_per_user × 12
Illustrative Annual Slack Pro Cost	105 USD/user/year	monthly_slack_pro_per_user × 12
Illustrative Incremental TCO for Hybrid Stack	255 USD/user/year	m365_cost + slack_cost

Pros & cons

Pros

Teams: Deep integration with the broader Microsoft product ecosystem.
Teams: Leverages existing Microsoft service agreements, which may influence the overall cost structure.
Slack: Highly modular platform featuring a robust marketplace for third-party apps and custom agents.
Slack: Specialized features like Slack Connect for external collaboration and Workflow Builder for task automation.
Slack: Integrated AI-powered agents and search capabilities designed to unify tech stacks.

Cons

Teams: Desktop application performance can be resource-intensive depending on system configuration.
Teams: File management architecture relies on SharePoint, which requires specific administrative oversight.
Slack: Requires a separate vendor relationship and additional per-user licensing for advanced features.
Slack: Managing security and compliance across an external SaaS platform requires distinct administrative efforts.
Slack: Message history retention limits are tied to specific pricing tiers, requiring careful plan selection.

Assumptions

M365 Business Standard Pricing: 12.50 USD/user/month — Illustrative market rate for common M365 business tiers; user-adjustable.
Slack Pro Pricing: 8.75 USD/user/month — Illustrative market rate for Slack Pro; user-adjustable.
Illustrative scenario probability — The Microsoft-Centric Enterprise: 60% — A user-adjustable modeling weight used to compare scenarios; it is not a measured probability or forecast.
Illustrative scenario probability — The Agile Multi-Tool Environment: 25% — A user-adjustable modeling weight used to compare scenarios; it is not a measured probability or forecast.
Illustrative scenario probability — The Hybrid Cost-Optimizer: 15% — A user-adjustable modeling weight used to compare scenarios; it is not a measured probability or forecast.

Practical next steps

Audit the current software stack to determine if Microsoft 365 is a pre-existing commitment.
Identify the primary workflow requirements, specifically whether the team relies on Microsoft-native document co-authoring or a diverse set of third-party SaaS tools.
Calculate the total annual cost for the entire staff on both platforms based on current user counts.
Review industry-specific compliance requirements regarding data residency and message retention policies.
Execute a 30-day pilot program with a cross-functional team to assess tool adoption and integration efficacy.
Finalize the decision based on the balance of integration efficiency, user feedback, and total cost of ownership.

Methodology

This report synthesizes official vendor documentation regarding product features. Calculations are provided as illustrative scenarios to assist in TCO estimation. All numeric inputs are illustrative and should be adjusted by the user based on their specific enterprise agreements. Scenario probabilities are schema-required modeling weights and are not empirical forecasts.

Sources

Sources support specific claims; they do not replace our analysis. Read the research and source standards.

FAQ

Does Slack offer a free version for history retention?: Slack offers a free plan that includes access to a limited history of messages and files. Organizations requiring long-term, searchable history should review the specific retention limits associated with their chosen paid plan.
Is Microsoft Teams included in Microsoft 365?: Microsoft Teams is a component of many Microsoft 365 business subscriptions. Organizations should verify their specific license agreement to confirm inclusion and feature availability.
How do these tools differ in their approach to external collaboration?: Slack provides Slack Connect for working with external partners, while Microsoft Teams utilizes Guest Access. The choice depends on the organization's existing security and identity management policies.

Related decisions

How do I migrate message history from Slack to Microsoft Teams?
What are the security differences between Slack Enterprise Grid and Microsoft Teams?

Disclaimers

Pricing and feature availability are based on standard market rates and may vary significantly based on enterprise agreements, regional discounts, or promotional offers.

This report is for informational purposes and does not constitute professional IT consulting or financial advice.

Scenario probabilities are illustrative modeling weights and are not empirical data.