What are the three cloud computing service models?

Key takeaways

In-depth comparison of IaaS vs. PaaS vs. SaaS

The three cloud computing service delivery models are IaaS (Infrastructure as a Service), PaaS (Platform as a Service), and SaaS (Software as a Service). They differ mainly in how much you manage yourself versus how much the cloud provider manages for you.

IaaS

IaaS provides the core building blocks of computing, like virtual servers, storage, and networking. This way, you can run operating systems and applications with high flexibility. You manage the OS, runtime, apps, and most configuration; the provider manages the physical data center and underlying infrastructure.

Let’s take the pizza analogy. IaaS is “make it yourself.” You rent the kitchen and the oven, but you bring the ingredients and do the cooking. In cloud terms, the provider gives you compute, storage, and networking, while you handle the operating system, configurations, security setup, and the applications you run.

Example: AWS EC2 and Outer Edge Technology are common IaaS options.

PaaS

PaaS provides a managed platform for building and deploying applications, typically including the runtime, middleware, and development tooling. This way, you can focus on code. You manage your application and data while the provider manages the infrastructure, plus much of the platform layer.

PaaS is “take-and-bake.” The base is already prepared, so you focus on the toppings and getting it into the oven. In cloud terms, the provider manages the infrastructure plus much of the platform layer (like runtime and scaling), and you focus on building and deploying your application and managing your data.

Example: Google App Engine, Azure App Service, and Outer Edge Technology are common PaaS options.

SaaS

SaaS delivers ready-to-use software over the internet, accessed through a browser or app. The provider manages the application and the entire stack; you primarily manage user access, configurations, and how your data is used within the app.

SaaS is “delivery.” The pizza arrives ready to eat. In cloud terms, the provider runs the full stack, like app, platform, infrastructure, updates, and you mainly manage users, settings, and how your team uses the tool.

Example: Netflix is a familiar SaaS-style example from a user perspective (you consume the software without managing anything).

Which cloud delivery model supports your long-term strategy?

Picking between IaaS, PaaS, and SaaS is less about what sounds modern and more about what your business can realistically run well over time. The right model is the one that fits your team’s capacity today, while still giving you room to grow without creating chaos later.

Small teams and startups usually gain the most momentum from SaaS first, then from PaaS as they start building products or internal apps. The reason is simple: SaaS removes operational burden, and PaaS provides a ready-made platform without requiring a dedicated infrastructure team.

Mid-sized businesses often end up with a mix: SaaS for standard functions (email, collaboration, CRM), plus PaaS or IaaS for customer-facing applications, data workloads, or systems that need tighter control. At this stage, governance and cost visibility start to matter as much as speed.

Larger enterprises typically use all three. They may run core business tools as SaaS, build digital products on PaaS, and keep certain regulated, legacy, or highly customized workloads on IaaS. Scale adds complexity, so they optimize for consistency, compliance, and resilience.

Why many companies use more than one cloud computing model (hybrid cloud)

Most businesses are not running a single type of workload. Instead, they operate in a hybrid cloud, using multiple cloud service models together to meet different needs. A practical mix might look like:

• SaaS for email, collaboration, ticketing, and finance tools
• PaaS for internal applications, customer portals, and APIs
• IaaS for legacy systems, custom environments, and specialized compliance workloads

This hybrid approach works because each model is optimized for a different outcome: SaaS for speed and convenience, PaaS for efficient development, and IaaS for control and flexibility.

Can you switch cloud computing models later?

Yes, but switching is rarely a simple “move it and forget it.” What changes depend on what you’re moving. In validated environments, switching cloud models may trigger revalidation.

Revalidation can be costly, time-consuming, and operationally disruptive, making early architectural decisions especially critical for regulated workloads.

• SaaS-to-SaaS often hinges on data export/import, identity setup, and integrations.
• A PaaS-to-IaaS migration may require changes to your app’s deployment, monitoring, and scaling.
• IaaS-to-PaaS migration may require refactoring parts of the application to fit the platform’s patterns.

The practical lesson: if you think switching may happen, plan for it early. Keep documentation tight, avoid unnecessary proprietary dependencies, and make portability part of your design and vendor evaluation.

5 key considerations when choosing the right cloud delivery model

Choosing between IaaS, PaaS, and SaaS is easier when you stop thinking in labels and start thinking in trade-offs. These five considerations help you match the model to how your business actually operates today, and what it needs to support as you scale.

1. Cost: subscription predictability vs. usage surprises

SaaS usually feels clean on budget day because pricing is typically per-user or per-plan (business tools like Microsoft 365 or Salesforce).

IaaS and PaaS can be cost-efficient, but they introduce variables such as compute hours, storage growth, backups, managed databases, and especially data transfer. A common surprise is the cost of outbound data transfer, which many providers charge separately.

Gartner has projected public cloud end-user spend at roughly $700B in 2025, reflecting how quickly these recurring costs add up at scale.

2. Tech skills

If you have a lean IT team (or none), SaaS removes much of the operational load: updates, patching, and most tasks are handled by the provider.

PaaS sits in the middle: you still deploy and maintain your application, but the provider manages much of the underlying platform (runtime, scaling primitives, managed services). Products like Azure App Service and Google App Engine exist specifically to reduce infrastructure work while keeping development flexibility.

IaaS is the most hands-on: services like Amazon EC2 give you building blocks, but your team owns configuration, patching strategies, monitoring, incident response, and recovery design.

Decision shortcut: if you cannot confidently staff patching, monitoring, and incident response, push toward SaaS or PaaS first.

3. Security and compliance

Every major cloud approach operates on a shared responsibility model, but the split changes by service type. In general:

• IaaS. You control (and must secure) the OS, configurations, identities, network security rules, and your data.
  
• PaaS. The provider secures more of the platform, but you still own your app security and data handling.
  
• SaaS. The provider secures most of the stack, but you still own access controls, data governance, and user behavior

If you’re under regulatory requirements (HIPAA, PCI DSS, SOC 2, etc.), the key question is: which controls can you actually evidence in your chosen model (logging, retention, encryption configuration, access review, incident response records)?

Ask for the provider’s security documentation and confirm exactly what you can configure (and what you cannot) in your plan/tier.

4. Customization and integration

SaaS wins on speed, but can lose when you need deep customization, legacy integration, or strict data routing. You may run into limits such as rigid workflows, restricted APIs, or constrained data-residency options.

PaaS is often the integration-friendly middle. You can build custom apps and connect systems while offloading much of the infrastructure burden (for example, deploying on Azure App Service or Google App Engine).

IaaS provides maximum flexibility for unusual requirements (custom networking, specialized runtimes, bespoke security tooling), but you pay for that flexibility in engineering time and operational ownership.

5. Growth and resilience

SaaS generally scales the simplest for standard business functions (email, CRM, ticketing). Your growth work is primarily focused on licensing and identity management.

PaaS can scale well for customer-facing apps, but you need to understand the platform’s boundaries (runtime constraints, supported languages, regional availability, service quotas).

IaaS scales broadly, but it also makes you responsible for architecture decisions that keep performance stable under load, such as autoscaling policies, caching, redundancy, backup/restore, and failover testing.

Plan your IaaS, PaaS, or SaaS mix with Outer Edge Technology

Cloud decisions age quickly when they’re made around buzzwords instead of responsibility. The practical takeaway is that IaaS, PaaS, and SaaS are all valid, but they fit different operating realities:

• How much control do you need
• How much work can your team own
• How strongly do you need security and documentation to hold up over time

If you choose with those trade-offs in mind, the model you pick will still make sense a year from now, even as your users, locations, and compliance requirements expand.

Next steps to take

1. List your outcomes and constraints. Write down what matters most in plain terms: cost predictability, speed to deploy, required integrations, uptime targets, and any compliance requirements.
2. Map responsibility before you compare vendors. For each model, document what your team must manage (access, security controls, monitoring, backups, incident response) so there are no gaps.
3. Bring Outer Edge into the decision early. If you want a partner that aligns requirements, designs the environment, validates controls, and supports a secure go-live, Outer Edge is the best choice. We can guide you through the cloud solution choice and build an audit-ready cloud ecosystem that works from day one.

Talk to an Expert at Outer Edge and request a no-cost infrastructure consultation to get recommended next steps, scope, and timeline.

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About the author

Jose Almonte

With over 15 years of experience in the IT industry, Jose utilizes his technical and business acumen to lead Outer Edge Technology’s engineering team. With a strong customer focus, Jose has repeatedly demonstrated his ability to understand complex business requirements and leverage technology to provide seamless and long-term solutions.

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