SaaS Software as a Service
Software running in the cloud, accessed via browser, customer pays a subscription. Salesforce pioneered ~1999. Today the standard model for B2B software.
Top layer of the cloud pyramid: IaaS → PaaS → SaaS. Major examples: Salesforce, Google Workspace, Microsoft 365, Slack, Zoom, Notion, Figma, HubSpot. Business model: ARR (Annual Recurring Revenue), Net Revenue Retention. SaaS fatigue is a cultural counter-movement in 2024–25: companies consolidate tools, small teams build self-hosted. Open-Core is a hybrid model (open source core + paid SaaS).