How to build a SaaS app

Building a SaaS app means shipping a narrow first version that solves one customer problem, on a mainstream stack, with accounts, tenancy and billing designed in from the start. A small senior team can reach a first release within months. Most of the risk lies in scope and in early architecture choices that are costly to change.

Where do you start

Start with one problem for one type of customer, and write it as a sentence a customer would agree with. Then list the smallest set of features that solves it end to end. Everything else waits for the second version.

Talk to potential customers before building. Five conversations that confirm the problem are worth more than a month of code.

Which stack should you choose

Choose tools your team already knows and that many engineers can work with. A typical SaaS stack has a TypeScript or Python backend, a relational database such as PostgreSQL, a React-based frontend and a managed host. A backend platform such as Supabase can cover authentication, database and storage early on, as explained in what backend as a service is.

Novel technology adds risk without helping the customer. Spend your novelty budget on the product idea.

What must be designed early

A few decisions are hard to reverse, so make them deliberately:

• Tenancy. How customer data is separated. See multi-tenant architecture.
• Authentication and roles. Sign-in, teams, permissions and invitations.
• Billing. Plans, trials, invoices and what happens on failed payment. Use a payment provider rather than building your own.
• Data model. Names and relations that will still make sense in two years.

Almost everything else can change later.

How do you launch the first version

Release to a small group of real users as early as you can. Add basic monitoring, error tracking and backups before the first customer, since fixing these after an incident costs far more. Collect feedback weekly and let it decide the next features.

How big should the team be

A first release usually needs two to four senior engineers who cover backend, frontend and infrastructure between them, with a product owner who decides priorities. Our article on how many engineers you need goes through the sizing logic. Seniority matters more than headcount at this stage, because every early decision is a long-term one.

How do AI coding agents change the work

Agents speed up routine code, tests and migrations, which shortens the path to a first release. They also produce code quickly that nobody has read closely. Keep review habits strong, as described in how to review AI-generated code, and keep the architecture decisions with a senior engineer.

What does it cost to build

Cost follows team size and time. A senior team of two to four engineers over a few months is the usual range for a first release, and the monthly price per engineer is the main driver. Add hosting, a payment provider, monitoring and design. Fixed-scope programmes give certainty on the first version, while an embedded team gives flexibility once customers start asking for changes. Budget for the months after launch as well, since support and iteration take as much effort as the first build.

What this means when you hire through Miyagami

Every engineer is tested by an AI-native tech lead who works with AI every day. Senior full-stack engineers join your team from €5,600 a month, with a shortlist within 3 working days and no recruitment fee. For founders without a team, the Founders programme builds a product for €60,000 fixed over twelve weeks: Discover €10,000, Design €10,000 and Deliver €40,000. See how we vet for what is tested.

Short answers