SaaS, PaaS or IaaS? What is the difference & which one to choose?

Małgorzata Kawałkowska

Content Specialist

As you’re getting ready to develop your application in the cloud, at one point you will face an important decision to make: which cloud computing service model is the right one for your project? SaaS? PaaS? Or IaaS?  

If you’re not at home with all these cloud-related concepts, no worries. This post, prepared together with Łukasz Marcinek, Head of Cloud Engineering at Spyrosoft, will shed some light on the characteristics of SaaS, PaaS and IaaS, the differences between them, their advantages regarding specific business needs as well as possible risks that may go with them.  

After reading this short guide, you should hopefully get a clearer picture of which cloud computing service model will fit your project’s needs best. 

What is a cloud computing service model? 

A cloud service model specifies the scope of control over and responsibility for the infrastructure and data that can either be more on your side or the provider’s side. This way cloud service providers can meet different business needs. 

Don’t confuse cloud service models with cloud deployment models. These are two different pairs of shoes. Cloud deployment models specify who has access to and uses the cloud infrastructure: whether it’s you exclusively or you share it with other users. It can also be a combination of both. 

Read about cloud deployment models in more detail >> 

SaaS, PaaS and IaaS: characteristics, differences, pros and cons 

Let’s decode what stands behind these abbreviations and get into the details of each model. 

What is IaaS? 

IaaS (Infrastructure as a Service) model gives you access to servers, storage, network and includes virtualization. Your developers’ job is to take care of the operating system, middleware, runtime, data and application itself. IaaS is like taking a step away from on-premise because you don’t have to invest in and handle machine management – this is a third-party duty. However, you still must take care of updating the OS and your software. 

What are the advantages of IaaS? 

Easier to manage than on-premise

In comparison to on-premise, with IaaS you don’t have to think about a bunch of things related to security or configurations which consume a lot of time, resources and effort.  

It gives flexibility

You are free to install any operating system you want and configure the service according to your business needs. You can also control the resources such as memory, RAM, CPU, or what kind of drives you want to use what makes IaaS the most customizable option out of the three cloud service models. 

Less vendor lock-in worries 

With IaaS you’re not so closely tied to a specific cloud provider, so vendor lock-in is less of a problem in this case.  

Easier to migrate legacy apps 

Some apps may not be “cloud-ready” and need a specific setup that can be achieved with IaaS thanks to its configuration flexibility. 

What are the disadvantages of IaaS? 

You have to take care of updates and backups  

More control means more responsibility. In IaaS, your developers are in charge of keeping the environment up to date and do regular backups as part of the maintenance tasks. 

Requires expert knowledge to manage it 

Since a part of the configuration process as well as software maintenance is on the user’s end, you will need a team of IT specialists to handle that. 

When to use IaaS? 

IaaS will be a good choice if you want to have more control and decisiveness over the resources, operating system or applications to be used, but at the same time, you don’t mind investing time and effort in managing them.   

High flexibility makes IaaS a good option for big and complex projects, but of course, this is not always so, and everything depends on a specific case. 

Also, with IaaS it’s easier to migrate legacy apps to the cloud. IaaS offers the greatest configuration flexibility, so it’s possible to create a tailor-made setup that fits specific needs. 

What is PaaS? 

PaaS stands for Platform as a Service. This cloud computing service model provides your developers with the components for developing your software. You don’t have to worry about servers, storage, operating system, runtime, or virtualization. Your developers can instead focus their efforts on developing software. 

Perfect examples of PaaS are three basic services offered by main cloud providers: AWS Elastic Beanstalk, Azure App Service, or Google App Engine. All of them are dedicated to delivering your web applications in a quick way without any tasks for managing your environment (like OS and software components) by developers, who can focus on implementation. 

What are the advantages of PaaS? 

Shorter development time 

Since you don’t have to create and configure your own work environment and can use ready-made tools or options to do some routine tasks, you can develop your application much faster. 

Upgrades managed by the third party
You don’t need to worry about updating the OS or other components. It’s all vendor’s duty.  

Easier to scale up or down
In many cases, PaaS solutions are easier to scale than other ones. 

What are the disadvantages of PaaS? 

Not all applications are “cloud-ready” 

PaaS solutions also have some limits, so your application should be prepared to work in this model. Unfortunately, especially the older applications have a problem with this and often during the migration process we have to refactor them, or even rewrite them sometimes.  

Vendor lock-in problem 

When you decide to get a PaaS solution from a single vendor, in most cases you become tied to and dependent on that vendor. It may be hard to switch a PaaS provider if you wanted to and also the cloud-to-cloud migration process is often very difficult and costly. 

Can be slightly more expensive 

Compared to IaaS, PaaS services are often more pricey. However, it’s worth remembering that PaaS services reduce development time and make it easier to maintain your application in the future. In the long run, the effort put into the maintenance of an IaaS application can be even more expensive. 

When to use PaaS? 

PaaS is a way to go if you want to have bigger control over your software development without the concern about infrastructure management. It’s also a good option if you don’t want to build the whole environment from scratch and instead, you want to just get going with developing your project and have it ready faster, which is especially important for projects with tight deadlines and turnaround times.  

What is SaaS? 

Software as a Service (SaaS) is a cloud computing service model in which the provider develops and manages the software in the cloud environment, takes care of its maintenance, updates and support. As a customer you get the ready-made product - the software - the rest is the provider’s responsibility. 

Some well-known SaaS products on the market are Office 365, Salesforce, Google Workspace and Jira.   

What are the advantages of SaaS? 

You buy a read-made product that meets your business needs 

You get an up-and-running solution, that meets your business needs and doesn’t need development or handling its hosting. You can simply access it through the internet and start using it right away.  

No software development needed 

If you don’t have a developers team or you don’t want to reinvent the wheel, you can use a ready-made SaaS solution, that fits your needs.  

No initial setup costs 

You don’t need to worry about the implementation costs thanks to a convenient license model. Everything is covered within the monthly subscription.  

What are the disadvantages of SaaS? 

Less flexibility 

In general, SaaS allows for very limited customization.  Since it’s ready-made software, you usually can’t really tailor it to your specific business needs or develop it the way you want.  

Loss of control 

Since you have no control over the infrastructure, you need to trust the vendor in all matters, including security.  

It’s usually more expensive 

Since basically all the responsibility stays on the provider’s end, usually you must pay more for SaaS than for PaaS or IaaS. 

When to use SaaS? 

SaaS is a perfect option if you want to buy a ready-made product that works in the cloud and start using it right away. You don’t need a software development team in your company to take care of creating and managing the application. However, you trade the easiness and speed of setup for very limited customization and control.   

Can SaaS be implemented in a different cloud than the provider’s? 

SaaS, as well as PaaS and IaaS, are different sales models, not implementation methods. If you decide on SaaS, the vendor provides you with software ready to use in their cloud. If you want the software to be installed in your cloud, then this is what PaaS allows for.  

SaaS vs PaaS vs Iaas: what is the difference? 

The general difference between them is in the responsibility level. In all three cases “as a Service” means that the responsibility for managing the application or its infrastructure lies in a larger or smaller part on the supplier.  

In SaaS the provider takes full responsibility for managing both the infrastructure and software, while In IaaS the vendor is responsible for taking care basically only of the hardware, leaving the control over everything else to you. PaaS is somewhere in between: the responsibility for the app and data is yours, while the provider manages the rest. 

In layman’s terms, this could be compared to renting accommodation. IaaS is like renting a flat with no furniture. You basically get four walls and a roof, plus utilities. How PaaS works is similar to renting a flat with all the necessary furniture, but you must bring your everyday belongings, like pots and dishes. Using SaaS is like renting a fully equipped hotel apartment, you don’t have to worry about anything. 

SaaS, PaaS or IaaS: which cloud computing service model is for you? 

When it comes to choosing an option, consider how much responsibility you want, and are ready, to have on your side and what are your project requirements.  

Whether you want to kick off with your project in the shortest time and don’t need a highly customized solution, you don’t want to reinvent the wheel and create things that are already available from scratch, or maybe on the contrary: you prefer to have full control over the whole infrastructure and environment from A to Z.