Custom software costs: what are you really paying for?

What does building software really cost?

There is no fixed number. Custom software costs depend on what needs building, how many users and roles are involved, which integrations are required, and how strict the demands are around security and reliability.

As an indication: a small internal tool often sits in the lower thousands of euros, while an application with login, multiple roles and an integration quickly runs into several tens of thousands. These are ballpark figures, not quotes. The real price only follows from a concrete scope.

More important than the hourly rate is how many hours your project takes. An agency at 100 euros an hour that takes twice as long is more expensive than one at 140 euros that finishes in half the time. Look at the total investment and the pace, not the rate in isolation.

And do not budget for the build alone. Software you keep using needs maintenance, hosting and the occasional small extension. Those ongoing costs typically run at 15 to 25 percent of the build cost per year. Factor that in from the start, or you will get a nasty surprise a year later.

Which factors drive the price of a custom application?

The price of a custom application is driven by a handful of things. Once you understand them, you can steer costs yourself by trimming scope.

The biggest underestimate is almost always in the integrations and the data migration. Building a tidy form is predictable work; talking to a poorly documented external API or cleaning up old data is not. So when you get a quote, always dig into exactly which integrations are needed.

• Number of features and screens: every unique screen and workflow costs build time.
• User roles and permissions: a system with one type of user is far simpler than one with admins, customers and staff.
• Integrations: connecting to your accounting, a payment provider or an external API takes time, especially when that API is flaky.
• Security and compliance: requirements around personal data and the GDPR add up.
• Data migration: moving existing data out of an old system is often underestimated work.

Off-the-shelf vs custom: which is cheaper?

Off-the-shelf software is almost always cheaper to start with. You pay per month, build nothing, and can get going tomorrow. For many processes that is exactly good enough.

Custom only becomes interesting when the off-the-shelf option forces you to reshape your process around the software instead of the other way round. Or when monthly licence costs for dozens of users add up to a figure you could have built for.

The honest sum: put the annual licence cost of off-the-shelf next to the one-off build cost plus maintenance of custom. For custom, budget roughly 15 to 25 percent of the build cost per year for maintenance and hosting. Only when custom is cheaper over a few years, or clearly more valuable, is it worth the investment.

There is a middle road too. Often off-the-shelf covers the basics fine and the pain sits in one specific part of your process. Then you do not build everything, just that one piece of custom on top, or an integration that lets two systems work together. That is usually the cheapest route to something that genuinely fits your business.

When custom software is not worth the cost

Sometimes custom is simply the wrong choice, and we would rather say that up front than after the fact.

If solid off-the-shelf software exists that covers 90 percent of your process, do not build. The last 10 percent is rarely worth the investment to solve. And if your process has not settled yet, building is premature. You would be freezing assumptions into code that you will want to change next month.

For a generic function like accounting, email or a simple webshop: those markets are mature and the existing products are better than anything you would build on a reasonable budget. Custom pays off for a process that sets your business apart, not for one every business has.

• Off-the-shelf software exists that largely covers your process.
• Your process still changes weekly and has not settled.
• It is a generic function that mature products already handle well.
• The budget is out of proportion to the value the software delivers.

How do you keep build costs under control?

The biggest cost in custom software is not the building, but building the wrong things. You control that with scope and short iterations.

We deliberately work in short iterations: first the smallest piece that genuinely delivers value, then build on top based on what you see in practice. That fits the idea behind a minimum viable product: start small and learn before you build further. A good first step is often to build an MVP instead of the whole system at once.

It also helps to understand your process first. Sometimes the gain is not in new software but in improving business processes with AI or integrating AI into existing business software, rather than a whole new platform. To make the broader trade-off, read how having custom software built works in practice and what to watch for when choosing a software agency.