What is SaaS PaaS and IaaS

If you've ever sat through a technology conversation where someone casually threw out we're moving to a SaaS model or we're hosting on IaaS infrastructure and nodded along while having absolutely no idea what they meant, this post is for you.

SaaS, PaaS, and IaaS are three different ways of delivering software and computing over the internet. They describe different levels of the technology stack, and understanding the difference helps you make better decisions about the tools and services your business uses, communicate more clearly with technology partners, and avoid paying for more infrastructure than you actually need.

Let's work through each one properly.

The Analogy That Makes All Three Click

Before the definitions, an analogy that tends to make these concepts stick.

Think about pizza.

If you make pizza at home from scratch you buy the ingredients, you make the dough, you use your own oven that's the equivalent of managing your own servers on-premise. You control everything, you're responsible for everything.

If you order a pizza kit with pre-prepared dough and toppings delivered to your door you still cook it yourself, but someone else handled the preparation that's closer to IaaS.

If you order a pizza that arrives ready to eat, just needs reheating closer to PaaS. The hard work is done, you just add the finishing touches.

If you order delivery from a restaurant and they handle everything ingredients, cooking, delivery that's SaaS. You just eat.

Same outcome (pizza in your hands), different amounts of responsibility and control. The cloud service models work the same way.

SaaS Software as a Service

What it is: Software that you access through a web browser or app, hosted and managed entirely by the provider. You don't install it, you don't maintain it, you don't manage the servers it runs on. You just log in and use it.

The simple version: Software you use online, usually on a subscription basis.

Examples you almost certainly already use:

• Gmail or Outlook 365 email as a service
• Xero or QuickBooks accounting as a service
• Salesforce or HubSpot CRM as a service
• Slack or Microsoft Teams communication as a service
• Shopify eCommerce as a service
• Dropbox or Google Drive file storage as a service

If you're paying a monthly subscription to use software you access through a browser or an app, and someone else is responsible for keeping it running, backing it up, and updating it you're using SaaS.

Who manages what: The provider handles everything, the servers, the infrastructure, the software updates, the security patches, the backups. You manage your data and your account settings. Nothing else.

Why it matters for your business: The vast majority of software small businesses use in 2026 is SaaS. It's accessible from anywhere, doesn't require installation on individual computers, scales up and down with your subscription tier, and hands the technical maintenance burden entirely to someone else. For most business functions email, accounting, CRM, project management, file storage SaaS is the right model and is what you should be looking for.

The trade-offs: You're dependent on the provider's uptime, their security practices, and their pricing decisions. If Xero has an outage, your accounting software is unavailable and there's nothing you can do about it. If they raise their prices, you pay more or you migrate. You also have less customisation flexibility than if you built or managed the software yourself though for most businesses this is entirely acceptable.

PaaS Platform as a Service

What it is: A cloud environment that provides everything a developer needs to build, run, and manage applications without having to manage the underlying infrastructure. The servers, storage, networking, operating systems, and runtime environments are all handled by the provider. The developer just writes code and deploys it.

The simple version: A ready-made environment for building and running software, without managing servers.

Examples:

• Heroku developers deploy applications without configuring servers
• Google App Engine build and run applications on Google's infrastructure
• AWS Elastic Beanstalk deploy web applications on Amazon's cloud
• Microsoft Azure App Service run web apps on Azure infrastructure
• Vercel and Netlify deploy web applications from code repositories

Who manages what: The provider handles the infrastructure, operating system, runtime environment, middleware, and scaling. The developer (or development team) manages the application code and data.

Why it matters for your business: If your business is having software or applications built for you a custom web application, an internal tool, a mobile app backend the development team is likely using PaaS to host and run it. Understanding PaaS helps you ask the right questions: What platform is this hosted on? and Who manages the infrastructure? are important questions when commissioning custom software development.

PaaS is also relevant if you have technical staff building internal tools. It dramatically reduces the infrastructure work required, letting developers focus on writing useful software rather than managing servers.

The trade-offs: Less flexibility than managing your own infrastructure. You're dependent on the platform provider's capabilities and pricing. Some highly specific technical requirements can't be met within a PaaS environment and require dropping down to IaaS or self-managed infrastructure.

IaaS Infrastructure as a Service

What it is: Raw computing infrastructure servers, storage, networking delivered over the internet on a pay-as-you-use basis. You get virtual machines, storage volumes, and network resources that you configure and manage yourself. The provider maintains the physical hardware; everything above that is your responsibility.

The simple version: Renting computing power and storage in the cloud, managed by your technical team.

Examples:

• Amazon Web Services (AWS) the market leader. EC2 for compute, S3 for storage, RDS for databases, and hundreds of other services
• Google Cloud Platform Google's equivalent infrastructure
• Microsoft Azure Microsoft's cloud infrastructure
• DigitalOcean a more accessible IaaS option popular with smaller development teams

Who manages what: The provider manages the physical hardware, the data centre, the network connectivity, and the virtualisation layer. You manage everything above that the operating system, security configurations, software installations, databases, backups, scaling, and monitoring.

Why it matters for your business: IaaS is what sits underneath many of the other services in this guide. Your Shopify store runs on AWS. Netflix runs on AWS. Much of the internet runs on AWS, Google Cloud, or Azure infrastructure. If you have a custom web application, a complex website, or a software product, it's almost certainly hosted on IaaS either directly or through a PaaS layer that sits on top of IaaS.

As a business owner, you're most likely to encounter IaaS when commissioning a development agency for a custom product, when your IT team is managing your infrastructure, or when you're looking at the hosting costs for a web application that's been built for you.

The trade-offs: Maximum flexibility and control, at the cost of maximum responsibility. Managing IaaS properly requires real technical expertise in server security, performance optimisation, database management, backup systems, and scaling configuration. Most small businesses should not be managing raw IaaS infrastructure themselves. If you're using IaaS for something business-critical, you should have a qualified developer, DevOps engineer, or agency managing it for you.

How They Relate to Each Other

SaaS, PaaS, and IaaS sit at different levels of the same stack. IaaS is the foundation of raw computing resources. PaaS sits on top of IaaS and adds the development environment layer. SaaS sits on top of both a complete application that uses the infrastructure and platform layers underneath.

A useful way to think about it:

IaaS is the land and building materials. PaaS is a ready-built workshop with tools already installed. SaaS is a finished product delivered to your door.

Most SaaS products are built on PaaS environments that run on IaaS infrastructure. When you log into Xero, you're interacting with SaaS software that's almost certainly built on PaaS and running on IaaS underneath.

As a business owner, you'll interact most directly with SaaS. If you're commissioning custom software development, you'll care about PaaS. IaaS is generally relevant only if you have technical staff managing infrastructure or if you're reviewing the setup of a complex custom application.

Which One Does Your Business Need?

Most small businesses need all three, they just don't think about it that way because they mostly encounter SaaS without thinking about what's underneath.

Here's a practical guide:

For your everyday business tools email, accounting, CRM, project management, file storage, communication SaaS is the answer. You're probably already using SaaS for most of these. The question is whether you're using the right tools and getting good value from your subscriptions.

For custom software you're having built a web application, an internal tool, a customer-facing product PaaS or IaaS is relevant. You need to ask the development team or agency building it: what platform is this hosted on, who manages the infrastructure, and what are the ongoing costs? These are legitimate, important questions that a good development partner should answer clearly.

For managing your own infrastructure if you have technical staff who manage servers and infrastructure IaaS is probably what they're using. If nobody in your business has that expertise, you should not be managing raw IaaS yourself.

The Questions Worth Asking About Your Current Setup

A few questions that help you understand where your business currently sits:

For your software subscriptions: Are you reviewing your SaaS subscriptions regularly? It's very easy to accumulate SaaS subscriptions that are no longer being used or to be on a tier higher than you need. An annual audit of what you're paying for and whether you're using it is worth the hour it takes.

For any custom applications: Do you know what they're hosted on? Do you know who manages that infrastructure and what it costs? If the answer is we rely on the agency that built it and we're not sure, that's worth clarifying. You should understand and own the infrastructure your business-critical applications run on.

For future software decisions: Before committing to any new software platform, ask whether it's SaaS (subscription, no maintenance), PaaS-based (custom development, infrastructure managed by a platform), or IaaS-based (requires ongoing technical management). The answer affects your total cost of ownership and your reliance on technical expertise.

A Note on Hybrid Approaches

In practice, most businesses use a mix of all three without necessarily labelling it that way.

A typical small business in 2026 might use:

• Gmail for email (SaaS)
• Xero for accounting (SaaS)
• A custom-built web application deployed on Heroku (PaaS)
• File storage on AWS S3 (IaaS, but accessed through a developer rather than directly)
• Their website on managed WordPress cloud hosting (technically IaaS underneath, but abstracted by the managed service)

None of this is complicated to manage from a business perspective, most of it just works. The value of understanding these categories is being able to have informed conversations about technology decisions, ask the right questions when commissioning software, and understand what you're actually paying for.

How Weblynx Works With These Models

At Weblynx, we build products that use all three layers of the cloud model depending on what each client's product needs.

We build and integrate SaaS tools into client workflows. We develop custom applications that run on PaaS platforms. We architect and manage IaaS infrastructure for more complex products. And we advise clients on the right combination for their specific situation and budget.

If you're trying to understand your current technology setup, planning a new software product, or evaluating a move to cloud infrastructure we can help you map what you have, explain what it means in plain language, and recommend what makes sense for your business specifically.

What Weblynx offers for cloud services:

• Cloud architecture advice and infrastructure planning
• Custom application development on PaaS platforms
• IaaS infrastructure setup and management (AWS, Google Cloud, Azure)
• SaaS tool selection, integration, and workflow optimisation
• Cloud migration planning and execution
• Ongoing cloud infrastructure management

Want to understand your technology setup better? Get in touch for a free initial consultation. We'll map what you're currently using, explain what it all means, and give you honest advice on whether anything needs to change.

Visit weblynx.us or send us a message we'll come back to you within one working day.

More from the Weblynx blog:

What Is Cloud Hosting and Does Your Small Business Actually Need It?

Cloud Hosting vs Shared Hosting vs Dedicated Server What Is the Difference?

AWS vs Google Cloud vs Azure Which Is Right for Your Small Business?