What Is SaaS?

Software as a Service is a delivery model: customers use software operated by a provider rather than managing each installation themselves. Access is commonly sold by subscription, but pricing alone does not define SaaS. A web page with a monthly payment is not necessarily a software service.

How the model works

The provider operates the application, deploys updates and maintains the service. Customers access it through a browser, an app or an API. A customer account usually holds its users, data and billing relationship. One customer may have several team members with different permissions.

A product can serve many organisations from shared infrastructure while isolating their data. That is called multi-tenancy. Separate infrastructure for each customer is another option; SaaS does not require one particular database design.

SaaS versus a custom internal application

A custom application may be built for one business and operated only for its staff. A SaaS product is intended to deliver a repeatable service to customers. It therefore needs a repeatable way to create accounts, grant access, support users, release changes and handle the commercial relationship.

BookBed is a property management product built with Flutter, Firebase and Stripe. Callidus OS is a clinic platform built with React and Firebase. Their case studies show how different customer workflows shape the software; they do not imply that every SaaS product needs their feature set.

What changes when you sell a service

• Account boundaries: users must access only the organisations and records they are authorised to use.
• Access lifecycle: onboarding, invitations, role changes and account closure need defined behaviour.
• Billing lifecycle: trials, renewals, failed payments and cancellation must agree with product access.
• Operations: backups, incident handling, deployment and support continue after launch.
• Product decisions: shared features must work across customers without turning every request into a separate codebase.

What to measure

Recurring revenue, retention, churn and activation can help explain whether customers receive continuing value. Define each metric before comparing periods: customer churn and revenue churn answer different questions. A subscription dashboard alone does not show why someone stays or leaves.

If you are planning a first release, start with the SaaS MVP guide. For the data model, see multi-tenant SaaS.