IaaS vs PaaS vs SaaS: The Three Cloud Models Explained

IaaS vs PaaS vs SaaS: the short answer

IaaS, PaaS and SaaS are the three main cloud service models, and they differ by how much you manage yourself. IaaS gives you raw infrastructure (servers, storage, networking). PaaS gives you a ready platform to build and deploy apps on. SaaS gives you finished software you just log in and use.

Think of it as a sliding scale of responsibility. With IaaS you control the most and maintain the most; with SaaS the provider handles almost everything and you simply use the product. PaaS sits in the middle. These three models, often written together as IaaS PaaS SaaS, cover nearly every way a business consumes computing today.

The difference between IaaS PaaS and SaaS in one view

The cleanest way to understand the difference between IaaS PaaS and SaaS is to look at who manages what. Every cloud stack has layers, from the physical hardware at the bottom to the finished application at the top. Each model draws the line in a different place: the more you hand to the provider, the less you have to run yourself.

A useful mental image is the “pizza as a service” analogy that circulates in cloud circles: on-premises is making pizza from scratch at home, IaaS is a take-and-bake kit, PaaS is delivery to your door, and SaaS is eating out where the restaurant does everything. It is a lighthearted way to remember the same shared-responsibility idea the table shows.

What is IaaS (Infrastructure as a Service)?

IaaS delivers the raw building blocks of computing on demand: virtual machines, storage, and networking that you rent instead of buying and racking your own hardware. You get a bare environment and install the operating system, middleware, and applications yourself. The provider keeps the physical data center running; everything above the virtualization layer is yours.

Who IaaS is for. Teams that need fine-grained control and flexibility, want to migrate existing workloads without rewriting them, or run infrastructure that spikes and dips and should scale on a pay-as-you-go basis.

Real IaaS examples. Amazon Web Services (EC2, S3), Microsoft Azure Virtual Machines, Google Compute Engine, and DigitalOcean Droplets. If you want the full picture of the biggest one, read what is AWS.

What is PaaS (Platform as a Service)?

PaaS provides a ready-made platform for building, testing, and deploying applications without managing the servers or operating systems underneath. You push your code; the platform handles the runtime, databases, scaling, and infrastructure. It is the middle ground: more hands-off than IaaS, more customizable than SaaS.

Who PaaS is for. Development teams that want to ship features fast, run CI/CD pipelines, and stop worrying about server maintenance. It is ideal when your value is in the application you are building, not in operating the machine it runs on.

Real PaaS examples. Heroku, Google App Engine, Red Hat OpenShift, and modern deployment platforms like Vercel and Netlify. The blog you are reading, for instance, is built and deployed on exactly this kind of platform, so the site stays fast without anyone babysitting a server.

What is SaaS (Software as a Service)?

SaaS delivers complete, ready-to-use software over the internet, usually on a subscription. There is nothing to install, host, or maintain; you log in through a browser and the provider handles servers, updates, security, and backups. It is the most hands-off model, and the one almost every business already uses daily.

Who SaaS is for. Anyone who needs a working tool rather than a system to run: teams that want email, CRM, collaboration, accounting, or design software without an IT project behind it.

Real SaaS examples. Gmail, Salesforce, Slack, Microsoft 365, Zoom, and HubSpot. Even Netflix is, for the person watching, a SaaS product, while its backend leans on IaaS and PaaS underneath.

SaaS betekenis: the term explained for Dutch readers

Because so many buyers search in Dutch, it is worth noting the saas betekenis directly: “SaaS” stands for Software as a Service, software you rent and use over the internet instead of buying, installing, and maintaining it yourself. The saas betekenis is simply “ready-made software on subscription”, and it is the model behind most of the business apps you already log into.

SaaS vs PaaS vs IaaS: how the comparison flips

People search this comparison from every direction, and the ordering changes what they are weighing. Read top-down as saas vs paas vs iaas and you start from finished software and peel back toward raw infrastructure, which is how a business leader tends to think: “Can I just buy the tool, or do I need to build?” Read bottom-up as IaaS to SaaS and you start from the hardware and add convenience at each step.

The paas vs saas question usually comes down to whether you are building something custom or buying something finished. The saas vs paas line is about control and fit: SaaS is faster to adopt but you accept its limits, while PaaS lets you build exactly what you need on top of managed infrastructure. However you order it, saas vs paas vs iaas describes the same three layers of the same stack.

How to choose between IaaS, PaaS and SaaS

You rarely pick just one. Most companies run a mix: SaaS for standard business tools, PaaS to build and host their own product, and IaaS for workloads that need control. The right choice depends on what you are trying to do and how much you want to manage.

For most businesses, the practical question is build versus buy. If off-the-shelf SaaS covers the job, use it. If your competitive edge lives in a custom experience, whether a bespoke web app, a headless site, or an integrated platform, you move up into PaaS and sometimes IaaS to build it. That build-or-buy call is the same one behind commercial off-the-shelf software; we cover it in depth in what is COTS software.

Where this fits when you build a website or web app

Cloud models are more than an IT concern; they shape how your website and digital products are built. A modern site is often built on a PaaS deployment platform (fast, no servers to manage), pulls content from SaaS tools, and occasionally leans on IaaS for heavier custom needs. Getting the mix right is part of building something fast, secure, and cheap to run.

At Viralistic we make these calls for clients as part of custom website development, choosing the right platform underneath so the site is quick to load and easy to maintain. It pairs naturally with a headless CMS, where content lives in one system and a lean, fast frontend is deployed on a modern platform. The goal is never the trendiest stack; it is the setup that serves your business and your visitors.

Frequently asked questions

What is the difference between IaaS, PaaS and SaaS?

The difference is how much you manage yourself. IaaS gives you raw infrastructure and you manage the OS, runtime, and apps. PaaS gives you a platform to build on and you manage only your application. SaaS gives you finished software and you manage nothing but your own data and usage.

What are the four types of cloud computing?

The three service models are IaaS, PaaS and SaaS. A fourth, CaaS (Containers as a Service), is sometimes added; it sits between IaaS and PaaS and delivers managed container orchestration. Separately, cloud is also grouped by deployment type: public, private, and hybrid cloud.

Is Netflix SaaS, PaaS or IaaS?

For the viewer, Netflix is a SaaS product: you log in and stream, with nothing to install or maintain. Behind the scenes, Netflix builds on IaaS and PaaS, running much of its infrastructure on Amazon Web Services.

Is Gmail PaaS or SaaS?

Gmail is SaaS. It is finished software you use through a browser, with Google handling all the servers, updates, and maintenance. The underlying Google Cloud platform that developers build on is the PaaS and IaaS layer beneath it.

Which is cheaper: IaaS, PaaS or SaaS?

There is no single answer; it depends on scale and use. SaaS has the lowest upfront cost and no maintenance, which suits most standard needs. PaaS and IaaS can be more cost-effective at scale or for custom workloads, but they carry engineering and operations costs that SaaS hides.