SaaS, PaaS, and IaaS are three common terms that describe different kinds of service-based computing. In each case companies consume IT resources on-demand from external cloud providers, instead of purchasing physical assets like hardware equipment and software licenses outright.

The as-a-service model maximizes efficiency so it can be more economical than traditional alternatives. Organizations only pay for what they use, making costs easier to distribute and predict. New resources can be provisioned whenever they're needed, enabling rapid scaling in response to new business needs.

While SaaS, PaaS, and IaaS all share these benefits, each one targets different use cases and user groups. In this article, we'll look at how the three offerings slot into your tech stack and when you should choose one over another.

SaaS: Software as a Service

SaaS (Software as a Service) is the most frequently used of these terms. It refers to complete software that can be used in return for a recurring subscription fee. SaaS products are usually hosted in the cloud and accessed from a web browser or mobile device. The concept can also refer to desktop software that's similarly licensed, such as paying for Microsoft Office programs via a Microsoft 365 plan.

Some popular SaaS applications include Slack for messaging, GitHub for code hosting, and Stripe for payment billing. Each one of these gives you a ready-to-use platform that solves a particular problem for you.

SaaS solutions are usually continually delivered so they improve through their life. As part of the ongoing subscription, new features and security patches are delivered on a regular cadence, without requiring action from the end user.

Most SaaS providers offer several different payment tiers that allow you to select the combination of features you require. Extra users, storage quotas, and addon modules can be purchased when they become necessary, instead of paying for everything upfront.

PaaS: Platform as a Service

PaaS stands for Platform as a Service. Unlike a SaaS, PaaS offerings don't target software end users. They're tools that development teams use to build, deploy, and maintain applications.

PaaS solutions abstract away the complexity of provisioning and running infrastructure. Developers used to set up servers manually by configuring the operating system, installing their programming language's runtime environment, and configuring admin tasks such as backups and monitoring.

PaaS services like Heroku and Firebase handle these tasks for you. They provide a ready-to-use environment that lets you deploy code automatically, each time you commit changes. The PaaS provider detects the source languages in your project, provides an appropriate runtime, and exposes your service to the internet.

Using a PaaS can provide significant time and cost savings to busy DevOps teams. They make deployments quick and easy, provide built-in scalability, and are usually easier to manage than self-hosted infrastructure. Most PaaS platforms include a graphical control panel that lets you monitor deployed apps and rollback problematic changes.

IaaS: Infrastructure as a Service

Infrastructure as a Service (IaaS) describes on-demand provisioning of new cloud computing components. Virtual servers are the most common form of IaaS but private networks, load balancers, and object storage systems can also fall under this heading. All the major cloud providers such as AWS, Azure, Google Cloud, and DigitalOcean became established by offering IaaS solutions.

Resources deployed from an IaaS provider are usually served using one of two models: shared or dedicated hosting. Shared hosting means several virtual compute resources owned by multiple customers are backed by the same physical hardware. This is more affordable but can harm performance if you've got "noisy neighbors." Dedicated hosting gives you exclusive use of a particular physical asset. It's akin to locating your own server in the cloud provider's datacentre.

Infrastructure as a Service cuts costs and offers greater flexibility than traditional on-premises servers. You're free to scale your resources up and down to satisfy changing customer demands and new product launches. You're in control of the virtual servers you provision so you can choose the operating system, install the packages you need, and fine-tune settings for maximum performance and reliability.

SaaS vs PaaS vs IaaS: Which Should You Use?

SaaS, PaaS, and IaaS each consider a unique aspect of cloud computing. If you're looking for new software to help run your business, a Software as a Service (SaaS) platform is what you should seek. Products marketed using this term are ready-to-use solutions which you can license on an ongoing basis.

PaaS and IaaS are more technical options aimed at developers and engineering teams. These solutions let you build and deliver your own SaaS products. Where they differ is in the level of control they provide.

A Platform as a Service (PaaS) lets you outsource your infrastructure so you can focus on your application's functionality. These solutions automatically build your code and deploy it to an appropriately configured environment. They can help you bring new products to market more quickly while reducing the maintenance burden over time. However PaaS approaches can prove limiting in the long-term as you're locked into the features of the platform you select.

Infrastructure as a Service (IaaS) gives you full control of your compute resources. You can provision and manage your own infrastructure components while benefiting from the scaling options of cloud services. The tradeoff is a greater maintenance burden as you'll be responsible for configuring and maintaining each system, as if it was a physical machine residing on your premises.

PaaS is usually the best choice for companies building straightforward SaaS solutions where rapid code releases are the top priority. IaaS is a better fit for organizations that are already managing their own tooling and want the greatest degree of control over their environment.

Summary

SaaS, PaaS, and IaaS are different forms of cloud computing that allow you to purchase resources on a rolling service basis. This is often more flexible and economical than buying or licensing equipment outright.

The three models are not mutually exclusive. Businesses can use them all alongside each other: dedicated servers could be hosted on an IaaS platform, and application deployments might target a PaaS solution, all while administrative tasks such as payroll, project management, and HR are handled using third-party SaaS products.

Understanding the respective focus areas of SaaS, PaaS, and IaaS will help you select the optimal technology for each new scenario. Mixing and matching can be the most effective procurement approach, letting you enjoy the benefits of all three with minimal drawbacks. While IaaS and PaaS help deliver software solutions, SaaS is something that organizations can both consume and produce.