IaaS, PaaS, SaaS — what each one means and when to choose it

The cloud is layered. The same AWS or Azure account gives you raw VMs, a managed database, and a finished collaboration suite — but the operational implications are very different.

IaaS — Infrastructure as a Service

You rent the compute, storage and network. You install and operate everything above it. You own: the OS, patches, runtime, application. The provider owns: hardware, hypervisor, datacenter.

Pick when you need lift-and-shift, custom kernel modules, or tight control over the OS. Avoid when a managed service exists for the same workload.

PaaS — Platform as a Service

You bring code or a database; the provider runs the platform. App Service, Azure SQL, RDS, Cloud Run, Vercel — these are PaaS. You own: the code or schema. The provider owns: OS, runtime, scaling, patching.

Pick when the workload fits a standard runtime (web app, API, database). Lower operational overhead, faster delivery, usually cheaper at small to medium scale.

SaaS — Software as a Service

A finished application. Microsoft 365, Salesforce, Slack. You own: your data and configuration. The provider owns: everything else.

Pick when the problem is generic (email, CRM, helpdesk) and the SaaS is mature.

A simple selection rule

Start at SaaS. Move down the stack only when SaaS does not fit. Most companies skip layers in the wrong direction and end up running infrastructure they did not need to.

Mixed reality

Real environments are mixed. A typical KodingTech client runs:

• SaaS for productivity (Microsoft 365), CRM, helpdesk.
• PaaS for the few internal apps (App Service, Azure SQL).
• IaaS for one or two legacy systems waiting to be retired.

That mix is normal. Picking the right layer per workload is the work.