Cloud computing comes with a lot of acronyms, and three of them show up everywhere: SaaS, PaaS and IaaS. They sound similar, but they describe very different things, and picking the wrong one can mean paying for work you didn’t need to do (or doing work you could have avoided).
This guide explains SaaS vs PaaS vs IaaS in plain English, with real examples, a side-by-side comparison and a simple way to decide which one you actually need.
SaaS vs PaaS vs IaaS: the short answer
All three are ways of renting computing power over the internet instead of running everything on your own hardware. The difference is how much the provider manages for you:
- SaaS (Software as a Service): you rent a finished app. You just log in and use it.
- PaaS (Platform as a Service): you rent a ready-made platform to build and run your own apps.
- IaaS (Infrastructure as a Service): you rent the raw building blocks (servers, storage, networking) and set everything up yourself.
These are the three service models in the US National Institute of Standards and Technology’s widely used definition of cloud computing.
An easy way to remember it: the pizza analogy
- IaaS is like renting a kitchen. The oven and counters are there, but you buy the ingredients, make the dough and bake it yourself.
- PaaS is like a take-and-bake pizza. The base is ready; you add your own toppings and put it in the oven.
- SaaS is like ordering delivery. It arrives ready to eat.
The more someone else does, the less control you have, and the less work you have to do.
What is SaaS?
SaaS is complete software delivered over the internet, usually through a web browser, on a subscription. The provider runs and maintains everything. You manage only your account, your users and your data. (For the full picture, see our guide: What Is SaaS?)
Examples: Gmail, Microsoft 365, Slack, Zoom, Salesforce, Shopify, Canva.
Best for: everyday users and businesses who need a tool that just works.
What is PaaS?
PaaS gives developers a ready-made environment to build, test and run their own applications without worrying about servers, operating systems or updates underneath. You bring the code; the platform handles the rest.
Examples: Heroku, Google App Engine, AWS Elastic Beanstalk, Microsoft Azure App Service.
Best for: developers and startups who want to launch an app quickly without hiring someone to manage servers.
What is IaaS?
IaaS rents you virtual servers, storage and networking by the hour or month. You choose the operating system, install the software and handle security updates yourself. It’s the most flexible option, and the most hands-on.
Examples: Amazon EC2, Microsoft Azure Virtual Machines, Google Compute Engine, DigitalOcean.
Best for: IT teams that need full control, custom setups or the ability to move existing systems to the cloud.
SaaS vs PaaS vs IaaS: side-by-side comparison
| SaaS | PaaS | IaaS | |
|---|---|---|---|
| What you get | A finished app | A platform to build apps | Servers, storage, networking |
| Who uses it | Everyone | Developers | IT and DevOps teams |
| You manage | Users and data | Your code and data | OS, software, security, data |
| Provider manages | Almost everything | Servers, OS, runtime | Physical hardware and network |
| Control | Low | Medium | High |
| Technical skill needed | None | Coding | System administration |
| Example | Gmail | Heroku | Amazon EC2 |
Who is responsible for security?
Cloud providers use a “shared responsibility” approach. The provider always secures the physical data centers. After that, it depends on the model:
- SaaS: the provider secures the app. You’re responsible for strong passwords, two-factor authentication and who has access.
- PaaS: the provider secures the platform. You’re responsible for your code and its data.
- IaaS: the provider secures the hardware. You’re responsible for patching the operating system, firewalls and everything you install.
A common mistake is assuming “it’s in the cloud, so it’s secure.” Every model still leaves some security work with you.
How to choose: a quick guide
- Do you just need a tool to get work done? Choose SaaS. Most individuals and small businesses never need anything else.
- Are you building your own web app or website backend? Look at PaaS first. It gets you live faster.
- Do you need full control, special configurations or to move existing servers? IaaS is the right fit, if you have the skills to manage it.
Many businesses use all three at once: SaaS for email and accounting, PaaS for a customer app, and IaaS for a legacy system. Just keep an eye on the bills, since cloud costs creep up quietly. Our guide on how to reduce SaaS costs can help.
Quick answers
Is AWS SaaS, PaaS or IaaS?
Amazon Web Services offers all three. EC2 is IaaS, Elastic Beanstalk is PaaS, and AWS also sells ready-made software services.
Is WordPress SaaS?
It depends. WordPress.com is a hosted service you simply log in to, so it works like SaaS. Self-hosted WordPress (from WordPress.org) is software you install on your own hosting.
Where does AI fit in?
AI is now built into many SaaS tools, and cloud providers also offer AI models on PaaS-style platforms for developers. See AI in SaaS for what this means for everyday users.
The bottom line
SaaS vs PaaS vs IaaS comes down to one question: how much do you want to manage yourself? SaaS means almost nothing, PaaS means just your code, and IaaS means nearly everything above the hardware. For most people, SaaS is the answer; developers and IT teams will reach for PaaS and IaaS as their needs grow.
For the official definitions, see NIST’s Definition of Cloud Computing (SP 800-145).
