What SaaS is, and how to build one from Türkiye

What is the difference between SaaS and custom software?

The common definition is "software that runs in the cloud", but that does not draw the line: custom software runs in the cloud too. What decides it is the number of codebases. In SaaS there is one version serving everyone at once, and customer differences are handled by configuration. In custom software each client has their own version and their own release schedule.

That distinction also sets the business model. One codebase brings the marginal cost of a new customer close to zero — which is the only thing that makes SaaS attractive. A product that branches per client, by contrast, grows its maintenance cost linearly with customer count and never develops an economy of scale.

How do you serve many customers from one system?

One system serving many customers means every query carries the question "which customer". If that constraint is not put into the architecture on day one, adding it later is practically a rewrite — because it requires touching every point of data access.

The risk here is legal rather than technical: one customer's data becoming visible to another is not a fault but a personal data breach with a notification obligation. So the separation has to be enforced in one place that every query passes through; a rule left to a developer's memory eventually gets forgotten.

How do you sell SaaS internationally?

The most common mistake is trying to meet both columns with one solution. A payment stack built for international sales handles local-currency subscriptions poorly; one built domestically stalls on foreign-currency collection. Planning them separately is cheaper than migrating later.

How do you price a SaaS product?

Per-seat pricing is easy to set up and easy to understand, but it carries a perverse incentive: the customer shares accounts to keep the cost down and does not spread the product through the organisation. Which is exactly what you do not want in SaaS — spread is the mechanism that grows both revenue and stickiness.

The alternative is tying price to a measure that grows with the value delivered: transactions processed, records stored, notifications sent, locations connected. The test for the right measure: when the customer's business grows, does that number grow? If it does, the price grows naturally and you do not have to renegotiate it every year.

Can I turn software built for one client into a product?

Most SaaS products start as software written for one client, and that is a good start: the problem is real and the first customer is real. The break comes with the second customer — who wants something different, and two roads open.

• Branch: fast, satisfies that customer, and leaves five unmaintainable versions two years later.
• Turn it into configuration: slower, expensive the first time, and pays for itself by the third customer.
• Refuse: you do not have to take every request into the product; what defines a product is what it does not do.

The practical rule: a request from two different customers is a product feature; a request from one is a project. Project work is priced separately and does not enter the product's codebase.

Which metrics matter in SaaS?

Three numbers suffice at an early stage, and more of them are a distraction: monthly recurring revenue, churn, and the cost of acquiring a customer. The most misleading of those is revenue; revenue rising while churn is high is pouring water into a leaking bucket, and it looks like growth.

Which company structure suits a SaaS?

A limited company is enough to start and simpler to set up; a joint-stock structure is more flexible for share transfers and investor entry. The decision depends on whether you plan to raise: without a round in mind you can stay as you are, with one the conversion should happen before the round — doing it mid-round adds weeks.

How should subscription cancellation be handled?

Making cancellation hard appears to lower churn in the short term but carries two costs: complaints and reputation. Easy cancellation is also increasingly becoming a rule on subscription platforms. What works is making it easy and asking why; the reason data collected is the most honest source of what to fix in the product.

Should I offer a free plan?

A free plan only works if the product has a spread mechanism: if using it pulls other people in. Without spread a free plan is only cost, because it brings support load and converts poorly. The alternative is a time-limited trial: it gives the same chance to explore without leaving a permanent cost.

Whose responsibility are backups in SaaS?

Left out of the contract, the question gets asked at the first data loss and has no answer. Three things need writing down: backup frequency, retention period and restore time. Enterprise customers also ask to be able to export their own data — building that from the start beats it becoming a negotiation when a customer leaves.

“A request two customers made is a product feature; one customer made is a project, and it is priced separately.”