What makes SaaS different from a single-customer application
A SaaS product serves many customers from one codebase and usually one infrastructure. Every feature must respect tenant boundaries, so one customer can never see another's data, and configuration must vary per tenant without forking the code. Billing, plan limits, trials, onboarding emails, usage tracking and an internal admin console become core features rather than afterthoughts.
Operations change too. You release continuously to all customers at once, so automated testing, feature flags, staged rollouts and monitoring matter far more than in a project delivered to one client. Support teams need tools to view a tenant's setup and impersonate users safely to diagnose problems. Release notes and in-app announcements keep customers informed about changes.
Finally, the business model shapes the software. Pricing by seat, usage or feature tier determines what the system must measure and enforce, so pricing decisions should be made alongside architecture rather than after the product is built. Changing the pricing model after launch is possible, but much easier when entitlements live in one well-designed module.


