Software engineering / SaaS development

SaaS products
ready to scale.

From idea to a multi-tenant product that grows every week. Architecture, subscription billing, roles, onboarding and metrics: we build SaaS designed to serve thousands of customers from a single deployment —and to keep improving without pause.

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What it is

Software you rent,
not software you buy.

SaaS (Software as a Service) is software delivered by subscription and run in the cloud: the customer installs nothing and manages no servers; they open a browser, pay a monthly or annual fee and always use the latest version. You, as the provider, maintain one product for everyone: you update it once and everyone receives it at the same time.

The piece that makes this model possible is the multi-tenant architecture: a single application serves many customers at once, keeping each one’s data rigorously isolated. Every company sees only its own —its configuration, its users, its plans— even though they share the same infrastructure underneath. Designing that isolation well (who can see what, and how it is guaranteed) is the most important technical decision in the whole project: security, cost and the ability to scale all depend on it. It is part of our software engineering practice, applied to building a product rather than a one-off delivery.

Decisions that define your product

What has to be right
from the start.

Multi-tenant architecture

Shared data with logical isolation, a schema per customer, or a database per customer? Each option changes cost, isolation and complexity. Choosing wrong is expensive once you already have customers inside.

Subscription billing

Plans, pricing, free trials, proration, taxes, failed payments, plan changes… Recurring billing is a system in its own right, not a “pay” button.

Roles and permissions

In B2B, every customer has their own teams, admins and access levels. You need a flexible role model (RBAC) from the start, not patched in afterwards.

Onboarding

The first five minutes decide whether a customer stays. A guided setup, with sample data and a fast “first value”, is the difference between activation and churn.

Scaling

Serving 50 customers is not the same as serving 5,000. The architecture, the database and the background jobs must grow without rewriting the product.

Product metrics

MRR, activation, retention, churn, usage by feature… Without instrumenting the product from day one, you decide what to build next blindly.

What we build

The whole product,
not just the screen.

A SaaS is far more than the interface a customer sees. Underneath sits a system that charges, controls access and measures. This is what we put in place:

Multi-tenant architecture with data isolation
Authentication, SSO and roles and permissions (RBAC)
Billing and subscriptions (e.g. Stripe)
Admin panel for you and your customers
Guided onboarding and account management
Product analytics (MRR, activation, churn)
Public APIs, webhooks and integrations
Observability, backups and a recovery plan

Types of SaaS

What kind of product
you are building.

Type of SaaS	What it is	When it fits
Vertical niche SaaS	A specialised product for one specific industry (clinics, law firms, workshops, real estate).	When an industry has its own workflow that generic tools do not cover well.
Horizontal B2B SaaS	A tool useful for almost any company: project management, HR, invoicing, support.	When the problem is common across sectors and the challenge is to differentiate and activate fast.
Internal platform turned product	A system you already use in-house and decide to package and sell.	When your internal software solves a problem that other companies also have.
Self-service tool	A product customers try and buy on their own, with freemium or paid plans, no sales rep.	When price and value allow a sale with no friction or negotiation.
SaaS marketplace	A platform that connects supply and demand and intermediates the transaction and payment.	When value lies in the network of participants and in managing trust and payment.

The core idea

Good SaaS isn’t launched and done; it grows every week.

Why the model wins

Why the world
builds SaaS.

Recurring revenue (MRR)

Subscriptions turn one-off sales into predictable revenue month after month. It is the base a SaaS business is valued on.

Scalability

One product serves a single customer or ten thousand. Growing in customers does not mean growing at the same rate in cost or headcount.

Single deployment

You update once and every customer gets the improvement at the same time. No old versions to maintain, no installs to migrate.

Continuous improvement

A SaaS is never “finished”. Every week you can ship improvements, measure their effect and adjust course with real data.

Data to decide

You see which features get used, where customers get stuck and what predicts churn. The product tells you what to build next.

Lower cost to serve

By sharing infrastructure and automating onboarding, the cost of serving one more customer tends to fall as you grow.

From MVP to product

You don’t build it all
at once.

A SaaS is built in stages: first an MVP a real customer can use and pay for; then the search for product-market fit, refining what truly matters; and only then scaling. At every stage there are things that are non-negotiable.

Working MVPProduct-market fitScalingData isolationMulti-tenant securityGDPR complianceObservabilityAutomated testsCI/CDBackups and recoveryPerformance at scaleAPI documentation

Every stage is decided with data: we don’t scale something that hasn’t yet shown people want it. And security, data isolation and observability are done properly from the start, because fixing them late costs ten times as much.

The CPPA method

From an idea to a product
that sells itself.

Discovery and business model

We understand the problem, the market and the model: who you serve, which plans you will offer and how you charge. We define the MVP scope and the foundations of the multi-tenant architecture.

Multi-tenant architecture and MVP

We design the data isolation and role model everything will grow on. We build an MVP a real customer can use —and pay for— as soon as possible, without over-building.

Build and integration

We develop with automated tests and CI/CD: billing, onboarding, admin panel and APIs. We instrument the product to measure usage from day one.

Launch and scaling

We deploy with observability, track the metrics (activation, retention, churn) and evolve. The product grows with the business, week by week, not all at once.

Product examples

What it looks like
in practice.

Vertical niche SaaS

A specific industry problem
MVP with the essential workflow
First reference customers
Subscription billing
Industry-specific integrations
Expansion into new features

Internal platform turned product

An internal tool that already works
Multi-tenant data isolation
Admin panel per customer
Plans and billing
Onboarding for external customers
First sale outside the building

B2B tool with plans

Sign-up and free trial
Guided onboarding
Free / pro / business plans
Roles and teams per company
Automatic recurring billing
Upsells based on usage

SaaS marketplace

Supply and demand onboarding
Verification and profiles
Search and matching
Payment intermediated on the platform
Ratings and trust
Commission per transaction

Risks and mitigation

Where SaaS
products go wrong.

A SaaS is easy to start and hard to sustain. These are the risks that matter most and how we mitigate them:

Multi-tenant security

The biggest risk in a SaaS is one customer seeing another’s data. We mitigate it with isolation by design, strict access control and auditing of every query to sensitive data.

Scaling under pressure

A product doing well can fall over just as it grows fastest. We design the architecture to scale horizontally and add observability to see the limits before hitting them.

Churn

Customers who never reach the value leave. We fight it with onboarding that drives a fast “first value” and with metrics that flag when an account is going cold.

Cloud costs

A poorly optimised SaaS can eat its own margin in cloud bills. We measure cost per customer and optimise infrastructure and queries so the margin improves as you grow.

Frequently asked questions

What is a multi-tenant architecture and why does it matter?

Multi-tenant means that a single application serves many customers at once, keeping each one’s data rigorously isolated. Every company sees only its own data, with its own configuration and users, even though they share infrastructure underneath. Designing that isolation well is the most important decision in the project: security, cost and the ability to scale all depend on it.

Should we start with an MVP?

Almost always, yes. An MVP (minimum viable product) is the smallest version a real customer can use and pay for. It validates that the problem and the solution fit before investing in everything else. Building the whole product “just in case” is the most expensive way to discover something essential was missing. That said, an MVP is not a fragile prototype: the foundations (security, isolation) are done properly from the start.

How are billing and subscriptions handled?

With a specialised gateway (for example Stripe) integrated into the product: plans, pricing, free trials, proration, taxes, failed payments and plan changes. Recurring billing is a system in itself; we build it to run on its own and to let you change plans and prices without touching code each time.

Is it secure and GDPR-compliant?

Yes. We design with per-customer data isolation, least privilege, encryption in transit and at rest, auditable logs and backups with a recovery plan. We process data in line with the GDPR, document where it is hosted and sign the required data-processing agreements. Multi-tenant security is not a layer added at the end: it is part of the design.

How much does it cost and how long does it take?

A useful MVP is usually in production in weeks or a few months, not years. Cost depends on the product scope, the number of integrations and the complexity of billing and roles. We work in phases with a transparent budget: first a product that delivers value early, then we grow from there with real data.

Will the product scale as it grows?

That is the goal from the first line of code. The multi-tenant architecture, the database and the background jobs are designed to scale horizontally, and we add observability to see bottlenecks before they become a problem. Serving ten thousand customers should be a matter of infrastructure, not of rewriting the product.

Related services

Keep exploring.

Code editor showing the markup of a web application

Have a SaaS product idea?

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Want to see how we think through a product end to end? Read ourCPPA X-RAY on 100 Montaditos.

SaaS products
ready to scale.

Software you rent,
not software you buy.