Slack

Free Tier Ratings

Last Reviewed: 2026-03-23

Good for team coordination on marketing. 90-day history limit loses context.

Coordinate grant teams. 90-day limit problematic for multi-year grants.

Internal coordination only. External comms need email/CRM.

90-day limit loses institutional knowledge. Not for documentation storage.

90-day limit inappropriate for board communications that need retention.

Coordinate training. 90-day limit loses training materials context.

Team coordination for social. 10 integration limit constrains tools.

Coordinate campaigns internally. 10 integration limit may block email tools.

90-day limit loses research context. Not for research storage.

Team coordination. 90-day limit loses policy discussion history.

Event coordination works. History limit problematic for annual events.

90-day limit inappropriate for financial records needing retention.

Non-Generative ML Only

Does NOT train LLMs on customer data. Non-generative ML (emoji suggestions, channel recommendations, search) uses de-identified usage patterns — NOT message content. April 2025 clarification: ML models do not look at DM or channel message content.

Yes — Admin request

Org/Workspace Owner emails [email protected] with subject 'Slack Global model opt-out request' and workspace URL. Slack processes request and confirms. Generative AI never trains on customer data regardless of opt-out status.

Never

Slack AI stays within platform trust boundary. Customer data does not leave Slack's infrastructure. Third-party LLM providers have no access to customer data. No external training or human review.

90-Day Limit

Messages deleted after 90 days. Major limitation for institutional knowledge. Upgrade to Pro (FREE for nonprofits ≤250 members) for unlimited history.

SOC 2, ISO 27001/27017/27018/27701/42001

TLS 1.2+ in transit. AES-256 at rest. ISO 42001 (AI management system) certified. ISO 27701 (Privacy Information Management) certified. Strong baseline security across all plans.

Exceptional Nonprofit Discount

Pro plan free for nonprofits with ≤250 members. 85% off all paid plans for larger organizations. Apply at slack.com/help/articles/204368833. TechSoup verifies eligibility. Churches, hospitals, schools, and government organizations do not qualify.

85% Education Discount

85% off Pro, Business+, and Enterprise Grid for educational institutions. Apply separately through Slack for Education program.

90-Day History Limit on Free

Free plan deletes messages after 90 days. This is a major limitation for institutional knowledge. Upgrade to Pro (FREE for nonprofits ≤250) for unlimited history.

3-User Minimum on Paid Plans

Even with 2 users, you pay for 3 on Pro and Business+. Minimum $21.75/month on Pro at full price.

Enterprise Grid Lock-In

WARNING: Once you upgrade to Enterprise Grid, you CANNOT downgrade. Ever. Evaluate carefully before committing.

No LLM Training on Customer Data

Slack does not train large language models (generative AI) on customer data. AI features use off-the-shelf LLMs via RAG — models don't retain customer data after requests. Non-generative ML (emoji/channel/search recommendations) uses de-identified usage patterns, NOT message content per April 2025 clarification. Opt out by emailing [email protected] with subject 'Slack Global model opt-out request.'

AI Features Bundled Into Plans (June 2025 Change)

Slack AI add-on discontinued August 2025. Basic AI (conversation summaries, huddle notes) now included in Pro. Advanced AI (recaps, translations, file summaries, workflow automation, Slackbot personal agent) included in Business+ and Enterprise+. Enterprise search across third-party apps (Google Drive, Salesforce, GitHub, etc.) in Enterprise+ only. Slackbot (personal AI agent) GA January 13, 2026 for Business+ and Enterprise+.

Strong Security Certifications

SOC 2, SOC 3, ISO 27001/27017/27018/27701/42001 on all plans. ISO 42001 (AI management system) is a new certification as of 2025. HIPAA BAA available for Enterprise Grid and Enterprise+. FedRAMP Moderate authorized. GovSlack (separate instance) FedRAMP JAB High + DoD IL4 authorized (Dec 2025).

Common Sense Media: WARNING Rating

Common Sense Media rates Slack with a WARNING (not a pass) due to personalized advertising, data profiles created for ads, and user data used to target ads on third-party websites. This applies to the general Slack platform. Enterprise customers can negotiate stricter data handling terms.

2026-03

New Slack AI features rolling out March 25, 2026: message explanations, canvas content generation, AI workflow automation, expanded Slackbot capabilities, and daily channel recaps for Business+ and Enterprise+ users.

2026-01-13

Slackbot — Slack's personal AI agent — reached general availability for Business+ and Enterprise+ customers. Slackbot understands conversations, files, channels, and respects all existing permissions. Connects Slack data with Salesforce CRM data.

2025-12-09

GovSlack (government-specific Slack instance) achieved DoD Impact Level 4 (IL4) compliance authorization, adding to its existing FedRAMP JAB High status. Relevant only for defense/government nonprofits.

2025-08

Customers with Slack AI add-on transitioned to new plan versions at first renewal after August 17, 2025. Pro users lost advanced AI features unless upgrading to Business+.

2025-06

Major pricing/packaging update. Business+ increased to $15/user/month (from ~$12.50). New Enterprise+ plan introduced. AI features bundled into tiers. Slack AI add-on discontinued. Pro now includes basic AI. Business+ and Enterprise+ include full advanced AI suite.

2025-04-07

Slack published updated privacy principles clarifying AI/ML data use. Confirmed: non-generative ML models do NOT analyze message content — they use de-identified usage patterns only. Generative AI (Slack AI features) never trains on customer data. Opt-out process for ML training clarified via [email protected].

For organizations with 5+ staff

Pro is FREE for nonprofits ≤250 members — includes unlimited history and basic AI (conversation summaries, huddle notes). Apply at slack.com/help/articles/204368833. Larger orgs get 85% off. For advanced AI (Slackbot, recaps, translations), Business+ at 85% off = ~$2.25/user/month is the new sweet spot.

For organizations with fewer than 5 staff

Pro is FREE for nonprofits ≤250 members. Note 3-user minimum billing on paid plans for non-discount orgs. Free tier's 90-day limit is a major limitation — apply for nonprofit discount immediately if eligible.

For health data or vulnerable populations

Business+ (~$2.25/user with 85% discount) for SSO, compliance exports, and advanced security. Enterprise Grid required for HIPAA BAA and Enterprise Key Management. Do NOT store PHI or sensitive client data on Free or Pro tiers.