Software-as-a-Service is the cloud service model most people interact with every day, often without realizing it. Email in a browser, a CRM, a payroll product, a code repository, all SaaS. Behind the consumer-friendly surface is a specific technical definition and a specific commercial trade-off.
The NIST definition
NIST Special Publication 800-145 is the standard reference. It defines SaaS as a model where the consumer uses the provider’s applications running on a cloud infrastructure, accessed through a thin client (typically a browser) or a program interface. The consumer does not manage or control the underlying network, servers, operating systems, or storage. Configuration is limited to user-facing settings.
The last clause matters. In SaaS, you rent the application. You do not rent the machine it runs on, and you do not patch it, tune it, or move it. NIST puts SaaS at the top of a three-layer stack: SaaS sits on top of PaaS, which sits on top of IaaS.
From CAPEX to OPEX
Before SaaS, software was a capital expense. You bought a perpetual license, deployed it on hardware you owned, hired people to operate it, and amortized the cost over years. Upgrades were projects. Failed deployments cost six figures.
SaaS converted software into a monthly operating expense. The provider runs the software. You pay per seat, per workload, or per usage tick. The line item moves off the balance sheet and onto the income statement. The cash-flow profile flattens, and procurement gets easier. The trade-off is a recurring bill with no end date and a vendor holding the keys to your data.
This shift is the entire reason SaaS won. Finance teams prefer predictable monthly spend. IT teams prefer not running mail servers. Vendors prefer recurring revenue. The economics aligned, and the model spread.
SaaS runs on IaaS
This is the part most non-technical buyers miss. A SaaS company is itself a tenant of someone else’s infrastructure. Salesforce runs on a mix of its own data centres and hyperscaler capacity. Notion runs on AWS. Most B2B SaaS startups you have heard of run on AWS, GCP, or Azure.
When you sign a SaaS contract, you are inheriting the SaaS vendor’s infrastructure choices. Their region selection becomes your data residency. Their cloud provider’s jurisdiction becomes part of your legal exposure. Their egress costs shape their pricing toward you. The stack underneath matters even when you do not see it.
Where ZCP fits
ZCP does not sell end-user SaaS applications. ZCP is the IaaS layer, VMs, block and object storage, networking, and an open API, billed in CAD with zero egress fees and no data leaving the region you select.
Several of our customers are SaaS independent software vendors (ISVs) running multi-tenant applications on top of ZCP. For them, ZCP is the boring layer underneath: predictable pricing for unit economics, a single legal entity on the contract, and region selection enforced at the infrastructure layer rather than a marketing promise.
If you are building or operating a SaaS product and the underlying cloud bill is becoming unpredictable, or your customers are starting to ask where their data sits, ZCP is built for this conversation.