We explain in plain language what cloud-based software is, why it has become so widespread, and what it means both for businesses that use it and for those building their own product.
Updated: June 2026
The shortest answer to the question of what SaaS is: SaaS (Software as a Service) means software you use over the internet, usually through a subscription, rather than installing it on your computer. Many of the applications you use every day — for email, accounting, customer management or design — are in fact SaaS products; you open them in a browser, log in and start working with no installation hassle. This guide explains in plain language what SaaS is, how it works, how it differs from traditional software, what it brings to your business and what to keep in mind if you want to build your own SaaS product.
SaaS is short for 'Software as a Service'. Instead of buying software and installing it on your own computer or server, you use an application that the provider runs in the cloud, accessed over the internet. You typically reach it through a monthly or yearly subscription; you do not have to deal with buying licences, installing, updating or maintaining servers. The provider takes care of all that, and you simply use the application. That is why SaaS is also described as using software like a service rather than owning it like a product.
A SaaS application runs centrally in the provider's cloud infrastructure. You log in from your browser or an app; the data and processing logic sit on the provider's servers, not on your device. This lets you reach the same software from the office, from home or from your phone, and you see the same up-to-date version on every device. New features and security updates are rolled out in the background, with no installation needed on your part. Most SaaS products serve many customers at the same time; each customer's data is kept separate and isolated, yet they all share the same application core. This shared structure is what makes the service both scalable and sustainable.
The software runs not on your device but centrally on the provider's cloud infrastructure.
Instead of buying and installing a license, you use it through a regular subscription; maintenance sits with the provider.
You sign in from the browser and reach the same up-to-date version from the office, from home or from your phone.
With traditional software you buy a licence, install the program on your own computer or company server and take on the maintenance yourself; updates, backups and server costs are yours. With SaaS, the software runs in the provider's cloud and you subscribe for access. The key differences are: a regular, predictable subscription instead of a large upfront licence; the shift of the installation and maintenance burden from you to the provider; always using the latest version; and access from anywhere, on any device. Where traditional software is more like an asset you own once, SaaS is a continuously updated service you pay for as you use it.
SaaS offers practical advantages to many teams, from small businesses to large companies. The entry cost is low: instead of a large licence fee you start with a subscription and scale up as your needs grow, or down when they shrink. The burden of installation, server maintenance and updates disappears; your team focuses on the actual business rather than technical upkeep. Access from anywhere makes remote work and cross-team collaboration easier. New features arrive automatically, so the software does not fall behind over time. Because data is kept central and organised, backup and security are mostly the provider's responsibility too. All of this lets the business focus on its core work rather than on the software.
SaaS is not only a model you use; you may also want to offer your own software product in this model. A SaaS product that serves many customers at once rests on a multi-tenant architecture: all customers share the same platform core, but their data and access are isolated from one another. Built correctly, this lets you bring each new customer (tenant) on board quickly and repeatably, with no setup from scratch; your infrastructure is ready for growth. At Vendoor Digital we design SaaS infrastructure not with a ready-made template but tailored to your product and tenancy model: we set up tenant isolation and access rules from the start and build an architecture that scales as load increases. If you already have a product, it is also possible in most cases to migrate it gradually to a multi-tenant structure. You can find more detail on how we work and what we cover on our SaaS infrastructure page.
When building your own SaaS product there is no fixed price; the cost takes shape from several factors. First, scope: what your product will do, how many different tenants it serves and the features you want are the main drivers. Second, the tenancy model: how data is isolated and how access is set up affects the complexity of the architecture and therefore the effort. Third, your starting point: are you beginning from scratch, or migrating an existing product to a multi-tenant structure — a migration changes the scope of the work. Fourth, time and urgency: a tight schedule means more intensive use of resources. A realistic budget therefore comes not from a ready-made price list but from clarifying the scope; the more precisely you define your product and tenancy model together, the more predictable the cost becomes.
Not quite. Cloud computing is a broad framework for running software and data on servers over the internet. SaaS is one form of that framework: a ready-made application the end user works with directly and accesses through a subscription. So every SaaS relies on the cloud, but not every cloud service is SaaS.
Your data is kept in the provider's cloud infrastructure, isolated from other customers. Security depends largely on how the provider sets up access rules and backups. In a well-designed SaaS, each tenant's data and permissions are separated; one customer cannot access another's data.
It is an architecture in which all customers share the same application core, but their data and access are isolated from one another. The shared core makes maintenance easier and lowers costs; the isolation keeps each customer's data separate and secure. Most SaaS products work on this model.
No. We design the infrastructure not with a ready-made template but custom, to fit your product, your tenancy model and your growth plan. Migrating an existing product to a multi-tenant structure is also possible in most cases; we review the architecture and produce a step-by-step migration plan.
Are you building your own SaaS product? Let's clarify your product and tenancy model; let's design and deliver a growth-ready, multi-tenant infrastructure together.
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