IaaS gives you infrastructure such as virtual machines, storage and networking. PaaS provides a managed application platform. SaaS provides a finished software product. The useful distinction is how much of the stack your team must configure, secure and maintain.
| Model | What you obtain | What you still own |
|---|---|---|
| IaaS | Compute, storage and networking | Application stack and remaining infrastructure configuration. |
| PaaS | An application platform | Application, data and supported configuration. |
| SaaS | A finished software product | Users, process, data settings and integrations. |
IaaS: more control, more operating work
With infrastructure as a service, you can usually choose and configure the operating system and application stack within the provider’s supported options. This can suit a migration that needs familiar server behaviour or software that does not fit a managed platform.
For a customer portal, your team may operate the application servers, install updates and manage deployment tooling. The provider’s infrastructure availability does not automatically make the portal available: your application and database design still matter.
PaaS: a platform for your application
A platform service can take care of parts of deployment, runtime management or scaling. Your developers concentrate more on application behaviour and data. You accept the platform’s supported environments, limits and commercial model.
Managed Kubernetes sits on a spectrum rather than removing every platform task. A provider may manage the control plane while your team still owns workloads, access policies, cluster configuration and application recovery. Read the actual service boundary instead of relying on the PaaS label.
SaaS: buy the workflow
If a standard product meets the need, SaaS may avoid building and maintaining custom software. You configure users, workflows, integrations and data policies, while the supplier develops and operates the product.
That still requires due diligence: can you export data, control access, connect to existing systems and leave the service later? A subscription replaces some engineering work, but it does not remove ownership of the business process.
Decide with a real requirement
For a straightforward appointment workflow, first evaluate a suitable SaaS product. For a differentiating customer experience with custom logic, a managed platform may be appropriate. For a legacy application with specific system dependencies, IaaS may be the practical first step.
These choices can coexist. A company might use SaaS for collaboration, PaaS for a portal and IaaS for specialist software. There is no requirement to choose one model for the whole organisation.
Questions for a supplier
- Which layers do you operate, and which remain with us?
- What happens during upgrades, incidents and capacity changes?
- Where are production data, logs and backups stored?
- What are the export, recovery and exit procedures?
- Which costs grow with users, traffic, storage or support needs?
Use the answers to compare total ownership and fit. The service with the lowest infrastructure price is not necessarily the least expensive way to deliver the complete workflow.
Sources & further reading
Primary references for the technical background and regional statements in this guide. Planning examples and checklists are Novacom’s practical guidance; examples are illustrative unless explicitly identified as project experience.