Slack Technologies operates on a freemium SaaS (Software-as-a-Service) business model, generating revenue primarily through tiered subscription plans sold to organizations of all sizes — from two-person startups to global enterprises with hundreds of thousands of employees. The model has three core tiers. The Free plan allows unlimited users with limited message history (the most recent 90 days) and restricted integrations (10 apps). This plan is Slack's most powerful growth mechanism: it removes the barrier to trial and adoption, allowing teams to experience the product's value before committing to a paid plan. The Pro plan, designed for small and medium businesses, is priced per active user per month and unlocks unlimited message history, unlimited integrations, group video calls, and enhanced administrative controls. The Business+ plan serves larger organizations and adds features like SAML-based SSO, data exports, and SLA guarantees. The Enterprise Grid plan — Slack's highest tier — is a custom-priced offering for large enterprises and regulated industries, providing centralized administration across multiple workspaces, compliance tools, and dedicated customer success management. This per-seat, per-month pricing structure means Slack's revenue is tightly correlated with two metrics: the number of organizations on paid plans and the number of active users within those organizations. Both metrics are influenced by the same flywheel: value delivered to individual users drives team adoption, which drives departmental rollout, which drives enterprise-wide licensing. Slack calls this the "land and expand" model — land a team of 10, expand to a company of 10,000. The network effects built into this model are significant. Every new user who joins a Slack workspace increases the value of the platform for everyone already in it. Every external partner or client invited into a Slack Connect channel becomes a potential new Slack customer. The product effectively markets itself through its own use. Revenue from Slack was reported separately in Salesforce's financials until fiscal year 2023. In FY2022 (the first full year post-acquisition), Slack contributed approximately $1.5 billion in annual revenue to Salesforce. By FY2023, this had grown to approximately $1.85 billion, and by FY2024, estimates placed Slack's contribution at approximately $2.1 billion. Salesforce no longer breaks out Slack revenue as a standalone segment, folding it into its broader "Platform and Other" category, which complicates independent analysis. Beyond subscriptions, Slack's business model has expanded in two important directions since the Salesforce acquisition. First, Slack is now deeply integrated into Salesforce's cross-sell motion. Salesforce account executives include Slack in enterprise deals, and Slack salespeople refer Salesforce CRM opportunities. This creates a co-selling dynamic where Slack's revenue indirectly supports Salesforce's total contract values. Second, the Slack App Directory has become an increasingly important part of the ecosystem. While Slack does not take a traditional revenue cut from third-party app developers the way Apple takes from the App Store, the directory creates lock-in: organizations that deeply integrate tools like Workday, ServiceNow, or Salesforce itself into Slack are significantly less likely to switch platforms. Slack's Dollar-Based Net Retention Rate (DBNRR) — a measure of how much existing customers expand their spending over time — was consistently above 125% prior to acquisition, indicating that existing customers reliably grew their Slack spend year over year. This metric is one of the clearest signals of product-market fit in enterprise SaaS and reflects the land-and-expand model working as designed. The transition to Salesforce ownership has shifted Slack's go-to-market strategy. Where Slack previously relied heavily on product-led growth and bottom-up adoption, the Salesforce distribution machine has added a top-down enterprise sales motion. Large enterprises are now approached by Salesforce account teams who position Slack not as a standalone messaging tool but as the collaboration layer for the Customer 360 platform. This dual motion — viral, product-led adoption from individual users combined with enterprise, sales-led deals from Salesforce's global salesforce — is Slack's most differentiated distribution advantage in the post-acquisition era.