Software as a Service

Software as a service (SaaS) is a delivery model in which an application runs on the vendor's infrastructure and customers use it over the internet, usually through a browser, under a subscription. Nothing is installed or maintained locally: the vendor handles hosting, updates, backups, security patches, and scaling, and every customer runs the same continuously updated version. Buyers trade a large upfront license for a recurring fee and much faster setup, while vendors gain predictable revenue and a single codebase to support. Salesforce established the model, and Slack, Notion, Figma, Zoom, and Shopify are familiar examples. SaaS sits above platform as a service and infrastructure as a service, which supply the runtime and raw compute the application is built on. AI features have pushed many vendors away from flat per-seat pricing toward usage-based or hybrid plans, because inference carries a real marginal cost per request. The recurring problems fall on the customer side. Data lives in the vendor's systems, so leaving requires an export path; per-seat costs accumulate quietly across departments into unmanaged spend; and availability depends entirely on the vendor, which makes status history and service level agreements part of the purchasing decision.