IaaS, PaaS and SaaS: what's the difference & how to choose between them

David Adamick
01 September 2021
9 min read

3 cloud computing models

If your head is in the cloud then it's likely you'll recognize the terms in this blog title, each with that double 'a' in the middle.  They refer, of course, to the three major cloud computing models in common use today: Infrastructure as a Service, Platform as a Service and Software as a Service.

If your head is not in the cloud but is thinking perhaps it should be, then read on: understanding these models, their capabilities, their pros and their cons are crucial to deciding which format is best for your business.

This post will take you through the difference between IaaS, PaaS and SaaS, what each offers, and which areas of your business will factor in determining the most suitable option.  So, let's look at:


  • The cloud

  • What is Iaas?

  • Pros & Cons of IaaS

  • What is PaaS?

  • Pros & Cons of PaaS

  • What is SaaS?

  • Pros & Cons of SaaS

  • PaaS vs IaaS

  • SaaS vs PaaS

  • Choosing a cloud computing service

  • Additional cloud service models

The cloud

As a refresher, cloud-based technology is about where and how your data is hosted, stored and managed. As this data is kept remotely across a variety of different servers, it is also - most crucially - about enabling software and services to be run via the internet instead of locally by one device.

Within this realm, SaaS, PaaS and IaaS, each offer a different capacity from simple database management to application development to full-on e-commerce systems.

Cloud computing pricing

Pricing structures for cloud-based services are divided into pay-per-use, subscription-based and hybrid, a combination of pay-per-use and subscription pricing.  Such flexibility can be a huge bonus for new businesses that require a storage capacity that is not only in line with their cash flows, but one that corresponds to their scaling-up rates.

IaaS - Infrastructure as a Service

IaaS is the most basic for providing cloud computing resources over the internet and is used primarily by businesses that don't want to maintain their data internally.

Instead, the cloud vendor will host the infrastructure elements that would normally exist in on-premises data centres, including networking hardware, servers, storage and virtualization layer.

As a result, IaaS helps companies build and manage data as they grow while allowing them to pay for storage space as and when it's needed, in turn providing them with an indispensably flexible resource.

Examples of IaaS 

  • Google Compute Engine - Built on the global infrastructure that runs Google's search engine and other services, it enables users to launch virtual machines on demand.

  • Microsoft Azure - A cloud computing service created by Microsoft for building, testing, deploying, and managing applications and services through Microsoft-managed data centers.

  • AWS (Amazon Web Services) - On-demand cloud computing platforms and APIs to individuals, companies, and governments, on a metered pay-as-you-go basis.

The pros of IaaS

  • Your business has complete control over the infrastructure you’ve hired out

  • Cost efficiency: a pay-as-you-go policy allows you to pay for resources as and when you need them.

  • Fully flexible downsizing and scaling up if needed.

  • No requirement for physical server nor maintenance.

  • Most providers offer free quotas on their services which allows businesses to develop and maintain small apps cheaper -- sometimes even for free

The cons of IaaS

  • The user is fully responsible for data maintenance, including the recovery of losses.

  • The user is responsible for the running of apps and operating systems.

  • All configuration is set at the user end.

  • As with cloud technology as a whole, control over security in IaaS is relinquished to the vendor. (This being said, providers usually have sufficiently-sized budgets to employ a level of security expertise to exceed those commonly found on-premises) 

  • Without the proper knowledge, IaaS can be used inefficiently and generate considerable costs

PaaS - Platform as a Service

When looking to host something beyond a static website, companies delving deeper into the cloud will employ PaaS for developing and deploying software applications over the internet, whilst also enjoying access to the most current tools to do so.

In this way, developers can create and host customized, consumer-oriented apps via a provided framework, with all servers, storage and networking managed by the cloud vendor. Developers maintain all created applications.

Examples of PaaS

  • Google App Engine - A cloud computing platform as a service for developing and hosting web applications in Google-managed data centres. Applications are sandboxed and run across multiple servers.

  • Heroku - One of the first cloud platforms (since 2007), and along with Ruby,  now supports Java, Node.js, Scala, Clojure, Python, PHP, and Go.

  • AWS Elastic Beanstalk - A platform offered by Amazon Web Services for deploying applications that orchestrate various AWS services, including EC2, S3, Simple Notification Service, CloudWatch, autoscaling, and Elastic Load Balancers.

The pros of PaaS

  • Enables easy, remote collaboration among the development team whilst remaining cost-effective.

  • PaaS platforms provide storage and computing infrastructures, text editing, version management and compiling and testing services.

  • Tools are easy to use and sign up for.

  • You can customize and update apps without having to worry about software upkeep on the backend.

  • Great flexibility and scalability for apps.

The cons of PaaS

  • Developers can only control what's on the platform - outages or hardware/OS issues will take software out with them.

  • Limited control of infrastructure behind the application.

  • As with all cloud models, potential security risk to app users as data is stored by the provider, not you.

  • Using tools offered by one provider means harder migration to another, should it be necessary. (For example, were Google Cloud Platform to increase pricing by 50% thereby prompting you to move elsewhere, your several existing Google tools would incur costly software changes, thus offsetting any savings.)  

SaaS - Software as a Service

The most common model in cloud computing, SaaS is the whole kit, offering cloud-based tools and apps for everyday use.

With SaaS, a company will have no need of downloading or installing any software to their current IT infrastructures and instead will have access to the most up-to-date software versions through an internet browser. The cloud vendor will oversee all maintenance and support.

Examples of SaaS 

  • Google Suite - The well-known workspace that comprised Gmail, Chat, Meet, Calendar; Drive for storage; Docs, Sheets, Slides, Forms, and Sites for collaboration; and an Admin panel and Vault for managing users and the services. 

  • HubSpot - Another popular CRM, marketing, sales, and service platform for connecting with and retaining customers.

  • JIRA - A project management software system via Atlassian that can be purchased on a subscription basis.

  • Dropbox -  A file hosting service offering cloud storage, file synchronization, personal cloud, and client software.

  • NetSuite - A cloud-based business management suite that includes ERP/financials, CRM and e-commerce facilities.

  • Slack - A business communication platform offering features such as topic-organized chat rooms, direct messaging and private groups.

The pros of SaaS

  • No requirement to manage or upgrade software.

  • No local resources are used (i.e. local server space).

  • No concerns about SaaS product upkeep.

  • SaaS products are easy to find and purchase.

  • A subscription policy that doesn’t come with huge upfront costs and can be scaled with business needs.

The cons of SaaS

  • No control over the cloud-based infrastructure (i.e. when the provider experiences outages, so do you).

  • Only the SaaS provider has control over security measures, meaning a breach or leak can expose your business's data.

  • Integrations tend to be only up to the provider and not 'patchable' on the user's end.

  • No ownership of the software – as you stop paying, so does your access to it stop. 

PaaS vs IaaS

The first and main difference between PaaS and IaaS is that with the latter, more direct control over operating systems is given whereas PaaS offers a user more flexibility and ease of operation.

If, for example, you needed to build a website, you would start with a single  IaaS product such as Google Cloud Storage for hosting it and its applications. 

However, if you wanted a more robust solution, with features that require usage of other IaaS services, you could reach for a PaaS product such as Heroku, or indeed Google App Engine, should you wish to stay with the same provider. 

You could consider IaaS as the foundation of building a cloud-based service for selling a physical product, upon which PaaS helps developers create customized apps via an API to be delivered over the cloud.

Another way of thinking about it is IaaS as individual  LEGO blocks and PaaS as a whole set. When you want to build a display quickly, you can combine pre-designed sets and be done with it. 

Should you prefer all constructions to be customized, however, this must be done via these single blocks. 

SaaS vs PaaS

With SaaS, products are fully managed by the provider, from the servers to the applications to the data, whereas PaaS products can be used as the basis upon which new products can be built and on top of the platform's network.

Should you need an app for your business, for example, you can start with a PaaS product that acts as a platform for the app to run on.  Once completed, that app could be considered SaaS from the user’s perspective since he or she is now being provided with a service.

SaaS is best for companies looking for a readily available, functional system that's easy to use, whereas  PaaS is better for companies needing to build a solution on an existing network.

In both cases, however, the functionality and security of tools can be compromised in the event of external data management issues.

Choosing a cloud-based service for your business

Saas for limited budgets

Since businesses do not have to design and develop their own software solutions, adopting software as a service can save them considerable time and money. This becomes particularly relevant where resources are limited and makes all the more sense when those products meet their business requirements. This means increased productivity, quicker.

PaaS for customization

Where there are fewer pressures on resources, medium and large businesses should consider the platform as a service model, particularly when customized apps are required to integrate with workflows and technologies.

IaaS for ultimate customization

Medium-sized and larger organizations with adequate IT resources might consider adopting infrastructure as a service. As they will thereby enjoy the almost complete control that IaaS allows, this means they can develop highly customized stacks to meet their specific business requirements. And should these requirements change, IaaS makes for easy technological adaptations.

Although similar, choosing among software as a service, platform as a service and infrastructure as a service means companies have to find the right balance between giving up control and saving their employees time and effort so they can be more productive.


To recap and round up, think of IaaS as the cornerstone of a cloud-based service for selling a product, be this content, software or a website itself. PaaS is then the platform for building apps without having to host them, and SaaS is the software you can purchase or sell to software companies to complete the picture.

Balancing the cloud

In the end, when considering which model is most suitable, the trick is for your business to strike the right balance between relinquishing control and affording your employees more time and freedom to be productive.

Additional cloud service models

Of course, with technology being what it is, it doesn't stop there. With the ongoing evolution of 'as-a-service' models, here are a few variants you'll likely be seeing more of in coming years:

  • FaaS Function as a service - A platform allowing customers to develop, run and manage application functionalities without the obligation of building and maintaining the infrastructure that is typical to developing and launching an app.

  • NaaS Network as a service  - Provides access to additional computing resources co-located with switches and routers. It includes WAN (wide area network), bandwidth-on-demand, flexible and extended VPN (virtual private network), security firewall, custom routing, multicast protocols, antivirus, intrusion detection and prevention, content monitoring, and filtering.

  • MaaS Monitoring as a service - For deploying monitoring applications online.

  • DBaaS Database as a service - Organizations can store and manage various databases without having to configure and maintain physical hardware.

  • CaaS Communications as a service - An enterprise communications tool you can lease that includes voice over IP, instant messaging, collaboration, and video conference apps using fixed and mobile devices.

  • STaaS Storage as a service - A cloud model for a small or medium-sized business lacking capital or IT resources through which it can rent space in a larger company's storage infrastructure.

With cloud computing technology these days, it really does seem as if the sky's the limit. If you'd like to find out more about how it might help your business fly higher, feel free to reach out to us at hello@start-up.house.


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