Software-as-a-Service (SaaS)

Software-as-a-Service (SaaS) is a cloud model where vendors host applications on remote servers and sell access by subscription, so you log in via a browser instead of installing software locally. SaaS turns software into a service, not a purchase.

SaaS sits alongside Infrastructure-as-a-Service (IaaS) and Platform-as-a-Service (PaaS) in the cloud stack. The difference is who it aims at: SaaS points at the end user, not at developers or operations teams.

You buy the finished product, whether that is email, a customer relationship management (CRM) system, or a payroll tool. The vendor carries the servers, the patches, and the uptime promise.

The category grew from niche webmail in the late 1990s into the default shape for business software. Gartner’s 2024 forecast for worldwide public cloud end-user spending put the SaaS segment at USD 247.2 billion, up from USD 197.0 billion the year before.

Support teams inside almost every business process outsourcing (BPO) contract run on SaaS: Salesforce for pipeline, Zendesk for tickets, Zoom for calls, Deel for payroll. Browse the full OA glossary for adjacent cloud terms.

Key takeaways

• SaaS delivers finished software over the internet on a recurring subscription, with no local install and no infrastructure to manage.
• It splits into horizontal (industry-agnostic) and vertical (single-sector) categories that share identical subscription plumbing.
• Global SaaS end-user spend reached USD 247.2 billion in 2024 per Gartner, USD 50.2 billion above the 2023 figure of USD 197.0 billion.
• Buyers trade upfront capital expenditure for ongoing operating cost — plus continuous updates and elastic seat counts.
• Data portability, integration depth, and vendor lock-in are the three questions worth asking every shortlist.

How it works

SaaS works by hosting the application on a vendor’s cloud servers and delivering it over the internet. Customers pay a recurring subscription, sign in through a browser, and the vendor manages upgrades, security, and uptime centrally for everyone at once.

The commercial mechanics are simple. Per-seat pricing suits Salesforce and HubSpot, per-usage billing suits Twilio and Snowflake, and flat-tier plans suit Notion and Slack.

Contracts run monthly or annually. Most per-seat agreements land somewhere between 12 and 36 months, and the shorter the term, the higher the per-seat rate usually sits.

The technical shape follows three layers. The vendor runs the hardware and operating system, sits its application on top, and exposes it over HTTPS through a browser, mobile app, or application programming interface (API).

Multi-tenancy means one code base serves every customer and gets patched in a single pass. Data belongs to the customer under the contract — the vendor owns availability, backups, and security.

Gartner’s sizing of the market shows how steep the curve has been across three consecutive years.

Read the two-year run end to end: USD 167.3 billion in 2022 against USD 247.2 billion in 2024 is USD 79.9 billion of new annual spend, a rise of roughly 48% across 24 months.

Because SaaS ships as web-based applications, most customers never need a web developer past the first integration step.

Support platforms get sized against busy-hour traffic patterns so call center queues stay inside service-level targets when volume peaks.

BetterCloud’s 2024 State of SaaSOps report tracks a steady year-on-year rise in apps per enterprise — which pushes buyers toward tighter identity and access controls.

Examples

SaaS splits into two families. Horizontal SaaS serves every industry with generic tools such as email and CRM. Vertical SaaS targets one sector, such as dentistry, construction, or life sciences. Both families share the same subscription plumbing.

Horizontal names carry most of the spend. Salesforce launched its CRM in 1999, Google Workspace arrived in 2006, and Microsoft 365 relaunched under that name in 2011.

Slack and Zoom both launched in 2013, and HubSpot has been selling since 2006. Each of them sells into any vertical that needs the underlying tool, which is what makes the category horizontal in the first place.

Vertical names own narrower ground. Toast serves restaurants with a point-of-sale (POS) and back-office stack, while Veeva Systems, which listed publicly in 2013, runs CRM and clinical software for pharmaceutical firms.

Procore covers construction and Guidewire covers insurance — each one dominant inside a single industry rather than across many. Their buyers pay for regulatory fit, not for breadth.

SaaS shows up across every outsourced function: customer service, design and graphics, digital marketing, human resources, lead generation and sales, payroll, and virtual assistant services.

Providers standardise on Salesforce, HubSpot, Zendesk, or Deel because the vendor handles the compliance load while the client keeps a portable data trail. Cloud-based tooling also means a new delivery site opens with a login list rather than a server order.

Teams sizing an outsourced function often model SaaS and on-premise cost side by side with an outsourcing calculator before they commit to either.

OA’s ultimate guide to outsourcing walks through the vendor-selection steps, and the Top 40 BPO companies in the Philippines list surfaces providers already running the major SaaS stacks. Learn more about OA if the sector is new to you.

Related terms

These terms sit closest to SaaS in the cloud cluster. Some name the layers running underneath it, one names the architecture that makes the subscription model affordable, and one names the commercial risk that builds up over a long contract.

• IaaS: infrastructure layer covering servers and storage, rented from a cloud provider.
• PaaS: platform layer with runtime and developer tooling that sits between IaaS and SaaS.
• Cloud Computing: umbrella term for on-demand compute, storage, and software delivered over the internet.
• Multi-Tenancy: architecture where one application instance serves many customers, isolated at the data layer.
• Vendor Lock-In: risk that moving away from a SaaS provider becomes too costly to justify.
• Scalability: capacity to add seats, storage, or throughput without rebuilding the service.

FAQ

These are the questions buyers ask most often before signing a SaaS contract. The answers cover the plain definition, how the model differs from cloud computing, the pricing shapes, the horizontal and vertical split, and the security posture worth checking.

What is SaaS in simple terms?

SaaS is software you rent by the month over the internet. The vendor runs it on their servers, and you sign in through a browser or app. Everyday examples include Gmail, Zoom, and Salesforce.

Is SaaS the same as cloud computing?

No. Cloud computing is the broader category covering infrastructure, platforms, and software delivered over the internet. SaaS is only the software layer of that stack.

How is SaaS priced?

Common models are per-seat monthly or annual subscriptions, per-usage billing tied to API calls or storage, and flat-tier plans with feature gates. Most contracts renew automatically unless you cancel before the term ends.

What are the main types of SaaS?

Horizontal SaaS sells generic tools across every industry, including Salesforce, Slack, and Zoom. Vertical SaaS targets one sector, such as construction (Procore), restaurants (Toast), or life sciences (Veeva).

Why do outsourcing providers rely on SaaS?

Providers standardise on SaaS because setup is fast, per-seat scaling matches headcount ramps, and every client sees the same tooling. Data portability also protects the client at contract end.

Is SaaS secure?

Reputable vendors publish SOC 2 or ISO 27001 attestations and encrypt data in transit and at rest, though buyers still own configuration, access controls, and identity hygiene.

Explore how leading BPO partners deploy SaaS at scale on the Outsource Accelerator hubs.