The three models in one line each
Choose IaaS when you want to run the server yourself, PaaS when you want to deploy code without managing an operating system, and SaaS when you only need the finished application. The three models differ in how much of the stack the provider runs, and each one is the wrong choice for some workloads.
- IaaS rents virtual servers, storage and networking. You install the OS, runtime and database, and you patch them.
- PaaS runs your application on a managed runtime. You push code, the provider handles servers, scaling and TLS.
- SaaS is a finished product you log in to. Nothing is deployed, because the vendor already runs it.
The old rule still holds: IaaS gives the most control and the most work, SaaS gives the least of both, PaaS sits between them. Pick the point on that line that matches the skills you have.
Who manages what on each model
The dividing line is the runtime. Above it, you own the application. Below it, the provider owns the machine. This table shows who patches what.
| Layer | IaaS | PaaS | SaaS |
|---|---|---|---|
| Application code | You | You | Provider |
| Runtime and middleware | You | Provider | Provider |
| Operating system and patches | You | Provider | Provider |
| Virtualisation and host | Provider | Provider | Provider |
| Network, storage, power | Provider | Provider | Provider |
| Accounts, permissions, data | You | You | Shared: yours to configure, theirs to secure |
Responsibility for data never leaves you. On all three models you decide who can log in, what is stored and how long it is kept. A provider hosting the database does not accept your customers' consent obligations for you.
Concrete examples of each model
Names help more than definitions. These are widely used services, listed by the layer they sell, not as a recommendation.
| Model | Examples | What you get |
|---|---|---|
| IaaS | AWS EC2, DigitalOcean Droplets, a WebJi® Linux VPS | A virtual machine with root, a network and a disk |
| PaaS | Heroku, Render, Vercel, Google App Engine | A deploy command and a running app with TLS |
| SaaS | Gmail, Google Workspace, Zoho CRM, Canva, Shopify | An account in software someone else operates |
Web hosting usually lands in IaaS or just above it. A cPanel shared plan is a managed platform for websites: you get a panel and a document root, not a kernel. A VPS is IaaS with a control panel bolted on.
When each model is the wrong choice
Each model fails in a predictable way. Knowing the failure saves a migration later.
- IaaS is wrong when nobody on the team will patch an OS, read a log, or restore a backup at 2am. The bill is low; the unmanaged risk is not.
- PaaS is wrong when you need a custom kernel module, a raw TCP port, a long-running daemon, or a filesystem the platform does not expose.
- SaaS is wrong when the vendor cannot meet your data residency, integration or exit requirements, or when the per-seat price outgrows a self-hosted equivalent.
Two smaller traps. A PaaS free tier that sleeps is not production. An IaaS bill without budgets and alerts can outrun a dedicated server in a quiet month.
Where a VPS or shared hosting fits
A VPS is IaaS at a fixed monthly price: root access, your choice of OS, and no per-second metering. That suits a team that wants the control of IaaS without the variable bill, and it keeps the database next to the application.
Shared hosting is the other end. It behaves like a restricted PaaS for websites: the panel manages PHP versions, certificates and mail, and you never see the operating system. For a brochure site or a small store that is the right amount of control.
WebJi® sells both. The shared hosting plans start at ₹300 per month before 18% GST, and VPS configurations are quoted by email before payment because disk, bandwidth and IP count change the number. We are a hosting provider in Jaipur, not a hyperscaler and not a SaaS vendor.
Cost and switching as you grow
The cheapest model at the start is usually the most expensive one to leave. A team that begins on PaaS often moves to IaaS when a background worker or a custom port appears, and that move means rebuilding deploys and backups.
Choose for the next twelve months, not the next month. If the product will need a queue worker, a cron job and a database you can tune, start on IaaS and skip the rebuild. If it is a frontend and a small API, PaaS will be cheaper than the hours you would spend patching.
Switching between models is normal, and the parts that survive are the same: versioned code, migrations, backups kept off the host, and environment variables in one place. A stack that can leave is a stack you can afford. Our SaaS hosting sizing guide covers the server side once you pick IaaS.
Frequently Asked Questions
What is the difference between SaaS, PaaS and IaaS?
IaaS rents virtual servers where you manage the operating system and everything above it. PaaS runs your code on a managed runtime, so the provider handles the OS and scaling. SaaS is a finished application the vendor operates and you simply log in to.
Is a VPS IaaS or PaaS?
A VPS is IaaS. You get a virtual machine, root access and a network, and you install and patch the operating system, runtime and database yourself. A control panel on top changes the convenience, not the model.
Which model should a small team start with?
Start with PaaS if the product is a web app with no background workers or custom ports, because it removes server maintenance. Start with IaaS when you need cron jobs, a queue worker, a tunable database or a fixed monthly bill.
What are examples of IaaS, PaaS and SaaS?
IaaS: AWS EC2, DigitalOcean Droplets, a WebJi® Linux VPS. PaaS: Heroku, Render, Vercel, Google App Engine. SaaS: Gmail, Google Workspace, Zoho CRM, Canva and Shopify. The list is about the layer each service sells, not a ranking.
Which cloud model is cheapest?
SaaS is cheapest to start because there is no infrastructure to run, and IaaS is usually cheapest at steady scale because you pay for a server rather than per seat or per request. Compare the total bill including the hours someone spends maintaining it.
Can I move between SaaS, PaaS and IaaS later?
Yes, and most teams do. Keep code versioned, migrations scripted, backups off the host and configuration in environment variables, and a move becomes a deploy rather than a rebuild. Moving to SaaS is the exception, since you replace the software instead of hosting it.