IaaS vs PaaS vs SaaS: what are the differences?

The meteoric expansion of new information technologies has, over the years, spawned new IT paradigms that have profoundly altered established practices. Among these disruptive concepts, cloud architectures have become the standard for companies wishing to take full advantage of the capabilities offered by outsourcing infrastructures and services. This new paradigm promotes the outsourcing of information systems to remote servers via the Internet. It comprises three main service categories: IaaS, PaaS and SaaS.


Definition of IaaS

IaaS stands for “Infrastructure as a Service”. Behind this term lies a very simple concept: providing a customer with raw computing resources, generally hosted in the cloud.

In concrete terms, an IaaS provider will make available storage capacity on remote servers, computing power or RAM. Customers can then deploy their own pre-configured virtual machines (VMs) on this outsourced infrastructure.

The customer retains full control over the configuration of the software layer.

The main advantages of the IaaS model are..:

  • Flexibility of use: companies can configure and adjust the virtual resources allocated to them according to their needs.
  • Elasticity: thanks to virtualization, companies can infinitely scale the capacities available to them, on demand, to cope with variations in business activity.
  • Cost optimization: outsourcing infrastructure to the cloud eliminates the costly capital and operating expenses associated with acquiring and maintaining physical servers.

In terms of use cases, IaaS excels for application development, with rapid deployment. It is also suitable for temporary projects requiring high scalability. Major players such as Amazon Web Services and Microsoft Azure have popularized this mode of cloud consumption.

Definition of PaaS

PaaS stands for “Platform as a Service”. In this case, the cloud provider offers the customer not just raw resources, but a complete application platform.

In practice, a PaaS player provides the server infrastructure, operating system, middleware and application management functionalities. Customers need only deploy their own application code on the platform. In this way, they retain control over their data and business logic.

The major advantage of PaaS is that it simplifies and accelerates development. Indeed, many services are natively integrated:

  • Databases
  • Message queues
  • Authentication
  • Cache
  • etc.

Hosting web and mobile applications is the preferred use case for PaaS. It is also used to create APIs or ready-to-use data integration chains.

Definition of SaaS

SaaS stands for “Software as a Service”. This is the most advanced model of cloud computing. With SaaS, the supplier makes a complete, operational application available online.

Here, the customer doesn’t have to worry about the underlying infrastructure or updates. All they need is an Internet connection to use the white-label software and access their data from anywhere.

SaaS applications can often be accessed via a web browser, but also via mobile or desktop apps.

The major advantage of SaaS lies in its ease of deployment. Customers avoid the time-consuming change management projects associated with on-premise solutions. SaaS applications can be found in most areas of business: corporate communications, sales management, finance, HR, etc. SaaS solutions are also available in a wide range of applications.

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The differences between models

IaaS, PaaS and SaaS each have their own specificities. It’s important to understand their differences before making your choice. The table below summarizes the main points of comparison:

Criteria IaaS PaaS SaaS
Service type

Raw resources (virtual machines, storage, networks, etc.)

Application platform (systems, middleware, software bricks, etc.) Fully operational software
Customer control  

Total SI


On application logic only Weak, limited parameterization

By the customer


Shared Total by supplier
Skills required  

Infra and operations experts


Application development Business users
Initial investment  



Medium Low



Medium Limited

At the customer’s expense


Shared By the supplier

AWS, Azure, Knowmore IaaS


AWS Elastic Beanstalk, Heroku, Knowmore App Platform Salesforce, Office 365, Knowmore KM Digital Workplace

The more control and responsibility are transferred to the cloud provider, the easier it is for the customer to use the solution. IaaS offers maximum flexibility, while SaaS enables accelerated but more constrained implementation. PaaS is the right balance for application projects.

Examples of SaaS, PaaS and IaaS on the market

Having theorized these concepts, it’s time to illustrate them with concrete cases from today’s cloud ecosystem.

For IaaS, AWS, Microsoft Azure and Google Cloud have the largest market share. These cloud computing giants enable companies such as Airbnb, General Electric and Netflix to host their IS flexibly and scalably.

In PaaS, the most widely adopted platforms are AWS Elastic Beanstalk, Heroku and RedHat OpenShift. They are driving the development of strategic applications at major accounts such as Thales, Sodexo, Fujitsu, Philips and BNP Paribas.

On the SaaS side, behemoths such as Salesforce, Microsoft Office 365 and Google Workspace equip a myriad of companies ranging from SMEs to major corporations. Salesforce supports prestigious customers such as L’Oréal, VMWare and GE, while Google Workspace boosts the productivity of teams at Whirlpool, Netflix, Airbus, Uber and Paypal.

These leading examples show that cloud computing has taken over all sectors. Its flexibility adapts to the needs of companies of all sizes, through IaaS, PaaS and SaaS.


IaaS, PaaS and SaaS embody the democratization of cloud computing. These modes of consuming virtualized IT resources have spread throughout the information systems of companies of all sizes.

However, these alternatives are not mutually exclusive. We are witnessing a growing convergence of cloud platforms, integrating several delivery modes. This hybridization gives companies greater freedom of choice, enabling them to tailor their strategy to their specific use cases.

The underlying trend is clear: the cloud is rapidly becoming an integral part of the information systems of public and private organizations. It is now an integral part of their digital agility, constantly adapting to market changes.

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