IaaS vs PaaS vs SaaS: A Complete Overview

Want to know more about IaaS, SaaS, and PaaS? Our in-depth guide includes a review of all three, plus tips to make the right choice for your business.

The cloud computing stack consists of three basic service models: Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). Many more XaaS service models exist, but IaaS, PaaS, and SaaS are considered basic cloud service models.

Organizations considering a transition to cloud computing should be prepared to examine a range of available options, address potential technical concerns, research the overall cost of the transition, and answer questions that may be raised in the process. Choosing the right cloud service model is arguably the most significant decision in this process. However, before making your choice, it is essential to understand the differences between various cloud service models and their pros and cons.
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As one moves up the stack from IaaS (the base layer) to SaaS (the topmost layer), the level of abstraction increases. The greater levels of abstraction enable customers to focus more of their attention on business rather than managing their IT infrastructure. Let's take a closer look at each of these service models:

What is IaaS?

Infrastructure as a Service (IaaS) is a service model that provides consumers with a range of virtual computing infrastructure: servers, storage, networking, memory, and computing; as a service. While the vendor is in charge of the hardware infrastructure, the customer's IT staff is responsible for installing, running, and managing the operating systems, software, and data.   

In an on-premise IT environment, the long procurement cycle for setting up and deploying physical hardware can take weeks, if not months. With IaaS, a virtual data center is available on-demand, and clients can set up additional resources within minutes. Besides annual or monthly subscriptions, IaaS is also available on a pay-as-you-go (PAYG) basis, where users are charged only for the computing resources they use. This model contrasts with the over-provisioning of resources and excess spending that occurs when running on-premise physical infrastructure. 

Since the IT infrastructure is virtualized, customers can direct their efforts toward building and managing applications while spending less time on IT heavy lifting.

Companies that provide IaaS capabilities are Amazon (AWS), Microsoft Azure, IBM, and Rackspace.

Advantages

• Useful in applications with a highly variable workload that require the IT infrastructure to scale up and down as per demand,
• Ideal for enterprises that wish to exercise a fair amount of control and administration over their applications and data,
• Low risk of vendor lock-in.

Disadvantages

• Virtual machines (VMs) can be exposed to security breaches in a multi-tenant environment,
• The workforce may need additional training to learn how to manage IaaS,
• Bills for high workload computing can be high.

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What is PaaS?

The next level up in the IaaS vs PaaS vs SaaS model is Platform as a Service (PaaS). In PaaS, the vendor provides a complete application development environment to the client, allowing them to develop and manage applications without building time-consuming development environments.

PaaS users also gain access to various resources in the application stack such as middleware, programming languages, operating systems, and databases. All of which would have been significantly more difficult to maintain on-premise.

A significant advantage of PaaS is that the need to reinvent the wheel is removed. Companies can leverage the APIs, to quickly assemble a collection of third-party solutions. The development team can pay a monthly fee and use resources to build and deploy applications faster than building from scratch.

Put simply, PaaS allows companies to focus on their core strengths and agile software development to provide superior results.

Popular examples of PaaS include Google App Engine, AWS Elastic Beanstalk, Force.com, Heroku, and Engine Yard.

Advantages

• Well-suited to applications that need to be deployed rapidly
• Streamlines workflows when multiple developers are working on the same application,
• Integrates well with many third-party solutions,
• Highly-scalable, like IaaS.

Disadvantages         

• Developers give up a certain degree of flexibility due to vendor lock-in,
• If a PaaS vendor has an outage, the customer must wait for the provider to resolve the issue.

What is SaaS?

One of the best-selling service models is Software as a Service. SaaS sits at the top of the IaaS vs PaaS vs SaaS cloud stack. When companies choose a SaaS option, the entire technology stack is outsourced. This means the vendor handles everything related to the delivery of the product.  Companies simply pay a subscription fee and access the application service over the internet through a web or mobile browser.

Since SaaS is delivered as a complete package, businesses do not have to spend precious time managing software and hardware. Instead, they can focus more on growing their business rather than be involved in IT.

Common SaaS products include Salesforce, GoogleApps, Hubspot, and Dropbox. The most popular SaaS solutions being business solutions like human resources, payroll, and enterprise resource planning.

Advantages

• Most likely to be used where speed-to-market is an essential driver for the organization,
• Products are easy to use and provide cost savings because of their multi-tenant environment,
• Solutions introduce high accessibility, well-suited for a remote workforce.

Disadvantages

• You don't have any control, as the vendor manages everything,
• There is a deluge of SaaS products in the market, which results in stiff competition,
• Vendor lock-in is a big issue.

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IaaS vs PaaS vs SaaS comparison

These cloud service models efficiently target different companies and industries. For example, IaaS can be an exciting option for organizations with an established IT infrastructure. With qualified staff, they can gradually migrate to the cloud instead of upgrading their on-premise infrastructure. It is also a viable option for start-up companies looking to avoid large capital expenditures on IT infrastructure.

PaaS solutions are an excellent asset for agile software development and deployment in large teams with remote workers. SaaS solutions target end-users who need a reliable and straightforward software solution that runs in a web browser.

As you move up the cloud service model stack, the required level of user IT expertise decreases. Meanwhile, the costs decrease as well. The SaaS cloud service model is the most affordable, while IaaS is the most expensive.

Generally, SaaS solutions high level of abstraction is better suited for companies and industries where IT infrastructure is less critical. Companies with more extensive IT infrastructure usually opt for lower levels of abstraction with PaaS and IaaS solutions. This allows more control over their applications and data, or gradually migrate from on-premise systems.

Gartner reports that SaaS solutions currently have the largest market share, continuing to push out traditional on-premise licensed software. IaaS solutions hold second place, with PaaS close behind in third place. However, Desktop as a Service (DaaS) solutions, despite their relatively small market share, is predicted to have the highest growth. This is likely due to the increased need for remote workers during the COVID-19 pandemic.

Our IaaS vs Paas vs Saas comparison should clarify the cloud service model that is ideally suited to meet the needs of your organization. Keep in mind that you can use a mix of these service models. For instance, you can use SaaS for your e-mail service and HR, and IaaS or PaaS to host the rest of your operations.

The specific requirements of a company should be the single most significant factor in determining the appropriate cloud service model.