What Is SaaS? Software as a Service Explained

SaaS is software delivered over the internet, paid for via recurring subscriptions instead of one-time licenses. The customer does not install anything. The vendor hosts, maintains, and updates the product. Revenue is predictable. Churn is the enemy.

SaaS = Software + Subscription + Cloud hosting
Traditional = Software + One-time license + Local install

SaaS (Software as a Service) is a software distribution model where applications are hosted in the cloud and accessed via a web browser. Customers pay a recurring fee (monthly or annual) instead of buying a perpetual license. The vendor handles infrastructure, updates, and security. Examples: Slack, Notion, Stripe, NoNoiseMetrics.

How SaaS Works

The SaaS model has three defining characteristics that separate it from traditional software:

1. Cloud-hosted. The software runs on the vendor’s servers (or a cloud provider like AWS/GCP). The customer accesses it through a browser or API. No downloads, no installations, no IT department required.

2. Subscription-based. Revenue comes from recurring payments — monthly, quarterly, or annual. This creates predictable cash flow for the vendor and lower upfront cost for the customer. The key metric is MRR (Monthly Recurring Revenue).

3. Continuously updated. Unlike packaged software with version releases (Office 2019, Photoshop CS6), SaaS products ship updates continuously. Every customer always runs the latest version. This eliminates version fragmentation and support complexity.

SaaS vs Traditional Software

Dimension	SaaS	Traditional Software
Delivery	Web browser / API	Downloaded, installed locally
Payment	Recurring subscription	One-time license fee
Updates	Continuous, automatic	Manual (version upgrades)
Hosting	Vendor’s cloud	Customer’s servers
Scaling	Instant (vendor handles)	Customer provisions hardware
Data	Stored in vendor’s cloud	Stored locally
Access	Anywhere with internet	On installed device
Revenue model	MRR/ARR (predictable)	Lump-sum (unpredictable)

The shift from traditional to SaaS is not just a delivery change — it fundamentally changes the economics. Traditional software companies had large upfront revenues and small maintenance fees. SaaS companies have small monthly revenues that compound over time. This makes churn the existential threat it never was for traditional software.

The SaaS Business Model

Revenue structure

SaaS revenue is measured in MRR (Monthly Recurring Revenue) and ARR (Annual Recurring Revenue). The relationship is simple: ARR = MRR × 12. See our MRR vs ARR guide for when to use each.

MRR has five components:

New MRR — revenue from new customers
Expansion MRR — upgrades, add-ons, seat additions from existing customers
Contraction MRR — downgrades from existing customers
Churned MRR — revenue lost from canceled customers
Reactivation MRR — revenue from returning customers

The sum of these movements is Net New MRR — the single most important growth indicator. Track it with the MRR dashboard template.

Pricing models

SaaS companies typically use one or more of these pricing models:

Flat rate — one price for everyone (e.g., Basecamp at $99/month)
Tiered — multiple plans with increasing features (Free / Growth / Enterprise)
Per-seat — price per user (e.g., Slack, Notion)
Usage-based — price scales with consumption (e.g., AWS, Twilio)
Freemium — free tier with paid upgrades (e.g., Dropbox, NoNoiseMetrics)

The choice of pricing model directly impacts ARPU, expansion potential, and churn behavior. See the SaaS pricing calculator to evaluate options.

Key SaaS Metrics

Running a SaaS business requires tracking a specific set of metrics that traditional businesses do not use. The core metrics:

Metric	What it measures	Why it matters
MRR	Monthly recurring revenue	Growth heartbeat
ARR	Annual recurring revenue	Fundraising & valuation
Churn Rate	% customers/revenue lost	Retention health
NRR	Net revenue retention	Expansion vs contraction
LTV	Customer lifetime value	Unit economics
CAC	Customer acquisition cost	Acquisition efficiency
ARPU	Avg revenue per user	Pricing health

For a complete reference, see our SaaS metrics glossary. Build your personalized metric stack with the metric stack builder.

SaaS Examples by Category

Project management: Asana, Monday.com, Linear, Notion Communication: Slack, Zoom, Microsoft Teams CRM: HubSpot, Salesforce, Pipedrive Payments: Stripe, Square, Paddle Analytics: Amplitude, Mixpanel, NoNoiseMetrics Email: Mailchimp, ConvertKit, Loops Infrastructure: AWS, Vercel, Supabase Design: Figma, Canva, Miro

What these all share: cloud delivery, subscription pricing, continuous updates, and a deep focus on retention metrics.

The SaaS Lifecycle

Every SaaS company moves through predictable stages:

1. Pre-PMF (Product-Market Fit). Building the product, finding early users, iterating based on feedback. Revenue: $0–$1K MRR. Metrics that matter: activation rate, early retention, qualitative NPS.

2. Finding traction. First paying customers, initial pricing, early distribution channels. Revenue: $1K–$10K MRR. Metrics: MRR growth, customer churn, ARPU.

3. Scaling. Repeatable acquisition, team building, market expansion. Revenue: $10K–$100K MRR. Metrics: NRR, LTV:CAC, cohort retention, CAC payback.

4. Maturity. Market leadership, profitability focus, potential exit. Revenue: $100K+ MRR. Metrics: Rule of 40, gross margin, net burn multiple.

The metric stack changes at each stage. Use the metric stack builder to generate the right set for your current revenue level.

Why SaaS Wins (and Where It Struggles)

Advantages

Predictable revenue. Monthly subscriptions create a revenue baseline that grows with customer count. This makes financial planning, hiring, and fundraising significantly easier than project-based or license-based models.

Lower customer barrier. No large upfront payment. No installation. No IT department approval (for self-serve SaaS). This widens the addressable market dramatically.

Compounding retention. Every retained customer contributes to next month’s MRR. After 3 years of 95% monthly retention, a SaaS company still has 16% of its original customer base — and all the new customers acquired since then. The math is powerful.

Network effects. Collaboration SaaS (Slack, Notion, Figma) benefits from network effects: each new user within a team makes the product more valuable for the entire team.

Challenges

Churn compounds. The same math that makes retention powerful makes churn devastating. At 5% monthly churn, you lose 46% of customers annually. Growth requires constantly outrunning this loss.

Cash flow timing. Monthly billing means you pay for acquisition upfront but receive revenue over 12–36 months. CAC payback period is the critical constraint — if it exceeds 18 months, cash runs out before customers become profitable.

Competition is fast. Low barriers to entry mean competitors can build similar products quickly. Differentiation increasingly comes from brand, integrations, data moats, and switching costs — not just features.

How to Start a SaaS Business

For founders considering the SaaS model:

Find a painful problem in a specific audience. The more painful and specific, the easier to sell and retain.
Build the smallest version that delivers value. Ship in weeks, not months.
Charge from day one. Pricing validates demand. Free users teach you nothing about willingness to pay.
Track the right metrics. MRR, churn, activation rate. Not vanity metrics. Use the metric stack builder.
Obsess over retention. Acquiring 100 customers means nothing if 50 churn in 90 days. Fix retention before scaling acquisition.

FAQ

What does SaaS stand for?

SaaS stands for Software as a Service. It means software hosted in the cloud and sold via recurring subscriptions, as opposed to one-time license purchases with local installation.

What is an example of SaaS?

Slack (team communication), Notion (project management), Stripe (payments), and NoNoiseMetrics (Stripe analytics) are all SaaS products. They run in the cloud, charge monthly or annually, and update continuously.

How do SaaS companies make money?

Through recurring subscription revenue — monthly or annual payments from customers. The key metric is MRR (Monthly Recurring Revenue). Growth comes from acquiring new customers and expanding revenue from existing ones (upgrades, seat additions).

What is the difference between SaaS and cloud computing?

Cloud computing is the infrastructure (servers, storage, networking) that runs in data centers. SaaS is an application layer built on top of cloud computing. AWS is cloud computing. Slack is SaaS running on AWS.

Is SaaS the same as a subscription?

SaaS always involves subscriptions, but not all subscriptions are SaaS. Netflix is subscription-based but delivers media content, not software. SaaS specifically means cloud-hosted software applications sold via subscriptions.

What metrics should a SaaS founder track?

At minimum: MRR, churn rate, and ARPU. As you scale, add NRR, LTV:CAC ratio, cohort retention, and CAC payback period. See our full SaaS metrics glossary for definitions and formulas.