What is SaaS?

Software as a Service (SaaS) is a cloud delivery model in which a provider hosts an application – such as Microsoft 365, Salesforce, or Google Workspace – and users access it over the internet, typically through a browser, rather than installing and maintaining the software on local infrastructure.

Key takeaways

• SaaS delivers hosted applications over the internet with no local install.
• The provider handles hosting, patching, upgrades, and infrastructure.
• Most SaaS apps are consumed by subscription rather than a one-time license.
• Versa CASB and DLP secure SaaS use through the applications’ own APIs.
• SD-WAN performance monitoring picks the best path to SaaS applications.

On this page: Why it matters · How it works · Types · SaaS & Versa · FAQ

Why is SaaS important?

SaaS reshaped how organizations get software. Instead of buying licenses, provisioning servers, and running patch cycles in-house, IT teams subscribe to an application and the provider handles hosting, scaling, and updates. That shifts spending from capital to operating expense, shortens deployment to days, and keeps every user on the current version.

The tradeoff is control. Data that once sat behind a corporate firewall now lives in a provider’s cloud, reachable from any browser. Employees can adopt a SaaS tool with a credit card and no IT involvement – shadow IT – creating data flows security teams never approved. SaaS also changes traffic patterns: client-server traffic no longer stays inside the LAN, so the WAN path to each SaaS provider affects application performance.

What is SaaS?

In the SaaS model, one provider runs a single version of an application – typically multi-tenant, so many customers share the same infrastructure while their data stays logically separated – and customers consume it as a service rather than owning a copy. The provider handles the servers, code, and patching; the customer owns its own data, users, and configuration – the shared-responsibility model.

Access happens over standard internet protocols: a browser session for end users, and increasingly an API for automated integration. That API surface lets third-party security tools – including Versa’s – inspect and control SaaS use without sitting inside the application. SaaS is one of three classic NIST cloud service models, alongside Platform as a Service (PaaS), a runtime for custom applications, and Infrastructure as a Service (IaaS), raw compute, storage, and networking.

Types of SaaS

SaaS applications are usually grouped by the function they serve, though many span more than one category.

• Productivity and collaboration suites – Microsoft 365 and Google Workspace bundle email, document editing, and conferencing into one subscription.
• Business and CRM platforms – Salesforce, ServiceNow, and similar applications run core sales, service, and workflow processes entirely in the provider’s cloud.
• File storage and content collaboration – Box, Dropbox, Microsoft OneDrive and SharePoint, and Google Drive store and share files without on-premises servers.
• Team communication – Slack, Microsoft Teams, Cisco Webex Teams, and Zoom carry chat, voice, and video traffic between distributed teams.
• Developer and project tools – GitHub, GitLab, Jira, Confluence, and Trello host source code, issue tracking, and project workflows.

SaaS & Versa

Versa secures and optimizes SaaS use from three angles. API-based data protection connects directly to a SaaS application’s API – via OAuth 2.0 – to scan objects in motion and at rest across apps like Box, Salesforce, Google Drive, Microsoft OneDrive, Slack, and GitHub, enforcing CASB and DLP policy without sitting in the traffic path.

For unmanaged or clientless devices, application reverse proxy puts a Versa Cloud Gateway in front of SaaS applications such as Salesforce and Box, integrating with an identity provider over SAML so Zero Trust, CASB, and DLP policies enforce in real time.

On the networking side, SaaS application monitoring lets Secure SD-WAN measure each WAN link’s performance to a given SaaS application – passively from live traffic or actively with HTTP, TCP, and ICMP probes – and steer traffic over the best-performing path.

Frequently asked questions

What is the difference between SaaS and IaaS?

SaaS delivers a complete, ready-to-use application, such as Salesforce – the provider manages everything below the application layer. IaaS delivers only the underlying compute, storage, and networking, such as AWS virtual machines, leaving the customer to install and run their own software on top.

What is the difference between SaaS and PaaS?

SaaS gives users a finished application to consume as-is, with nothing to build. PaaS gives developers a managed runtime – application servers, databases, deployment pipelines – for building and running their own custom applications, without managing the servers or operating system underneath.

How is SaaS typically priced?

Most SaaS applications sell by subscription, commonly billed per user, per month or per year, sometimes with usage-based add-ons layered on top. This replaces the traditional large upfront license purchase, spreading cost over time and tying spend to actual, ongoing usage.

What is shadow IT, and why does it matter for SaaS?

Shadow IT is any SaaS application employees adopt without IT or security approval – often just by signing up with a work email and a credit card. Because the data never touches an approved system, security teams have no visibility into it, a primary driver behind CASB adoption.

How does Versa secure SaaS application traffic without sitting inline?

Versa’s API-based data protection connects to a SaaS application’s own API using OAuth 2.0, scanning files, messages, and shared links for policy violations directly through the provider’s platform – complementing inline enforcement from application reverse proxy and SD-WAN application path selection.

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