Web applications14 October 20269 min

Custom software development cost, line by line, with three real jobs

Custom software development cost line by line: three priced jobs from 9,400 € to 27,000 €, what doubles the bill, and how to keep an MVP small.

In May the owner of a pool maintenance company in Aubagne brought me two quotes for the same app, one for 6,900 € and one for 58,000 €, and asked me which of the two was lying to her. She has eleven technicians and about four hundred pools on contract, and until then she'd planned the routes on a whiteboard with colored magnets, so she knew exactly what she wanted the app to do, but she couldn't see how custom software development cost could be eight times higher from one company to the next. Neither of them was lying, as it turned out. They were quoting for two different apps.

What I told her about custom software development cost is more or less what I tell everyone. At my studio a web app starts at 9,000 € before VAT, which is about $10,000, for one type of user, one process and one connection to a tool you already pay for, and it takes four to eight weeks. Most of the ones I've delivered have come in somewhere between 9,000 and 30,000 €, and after that there's 100 to 300 € a month for hosting and upkeep. I work it out in days, so every extra type of user or integration adds a few days to the price.

If you're not sure yet that it's an application you need and not a better website, the guide to custom web application development has the two questions I ask first.

What custom software development cost covers, line by line

Three years ago a restaurant owner in Marseille read my quote at his bar, turned it over to look at the back, and asked me if that was it, one number. Since then I've broken my quotes down line by line. This is the 9,000 € one, for the smallest app I build.

It comes to 900 € for the day on site and the written scope, 1,600 € for the mockup, 1,800 € for logins and permissions, 2,700 € for the screens, 1,000 € for one integration and 1,000 € for import, testing and switchover.

A boat rental company in Cassis asked me last year to leave out the day on site, since the manager had explained it all on the phone, and I agreed. When I went to the port in week four to try the screens on the dock, the man working there told me about a third of the rentals were paid in cash at eight in the morning, before the office opened, and the screens only took cards. The rework cost the client 1,400 €, more than the day on site would have.

None of the lines are monthly. The pool company's hosting, backups and updates come to 160 € a month on top, most of it for storing photos, and for apps of this size the range I see is 100 to 300 €.

Three jobs, three prices

9,400 €, allocations for a wine estate

I spent my day on site at the estate above Cassis in January, in the office next to the cellar, and most of it watching the owner's son answer the phone. They sell most of their white to about 120 wine shops and restaurants, there's never enough, and every January each customer is told how many cases they'll get, by email from a spreadsheet. That morning the replies were coming back by email and by phone, and he showed me one that had come on a postcard. Every one of them got typed back into the spreadsheet by hand, usually in the evening.

I built them a small client portal where each buyer confirms their own allocation or asks for more, and the estate moves cases around on the admin screen that comes with every app, so it was one type of user and one connection to their invoicing software, 9,000 € plus 400 € for a PDF of the pallet sheets that the cellar master wanted.

15,800 €, the pool company

In Aubagne I did the day on site in a van with one of the technicians, nine pools between Aubagne and Roquevaire. At four of them his phone had no signal at all, and he told me that's why nobody had ever managed to get them to fill anything in on the spot.

So the app keeps the report on the phone and sends it when the signal comes back, which was about 2,000 € of the 15,800 €, and the other 4,800 € over the base price went into the second type of user, since the office plans the routes on a laptop while the technicians work from their phones, and into the email each pool owner gets with two photos and the chlorine reading.

The 58,000 € quote was for native iPhone and Android apps, a login for the pool owners and a dashboard with twelve charts. She asked a few of her clients about the login before deciding, and none of them wanted one. The 6,900 € quote was a form builder billed per technician, and it couldn't plan the routes.

27,000 €, the one that doubled

At a marine electrics workshop in La Seyne-sur-Mer, near Toulon, the day on site went well and I estimated 13,500 €. Then I opened their Access database. The owner's nephew had built it in 2009, with three customer tables called clients, clients2 and CLIENTS NEW, and getting seventeen years of boats and invoices out of it took me longer than the app did. In week five the owner also asked for his subcontractors to have their own access, a third type of user, which I quoted in writing and he accepted. The final invoice was 27,000 €.

What doubles the bill

Four of my quotes from the last three years ended at about twice what I'd first estimated, and I reread all four for this article. The code wasn't the cause in any of them.

Here is what it was in each case:

a new type of user added during the build, twice (the subcontractors in La Seyne, and the drivers at a moving company in Gémenos);
the Access database in La Seyne;
accounting software with no API at a property manager in Toulon, so the app leaves it a file every night;
a main screen redrawn in week six, after the mockup had been approved in week three.

Out of everything I've built, one app had to be native, because it read a Bluetooth sensor on a boat engine and Safari on an iPhone doesn't let a web page do that. Everyone else got a web app, saved to their home screen like any other icon.

Payments cost less than expected at the wine estate. The big buyers pay a deposit through a payment link from the estate's bank, and connecting it took me a day and a half. A full checkout with deposits, refunds and two VAT rates would have been about two weeks.

At an insurance broker in Aubagne the expensive part of the brief was someone reading emails and typing them into other software, and that turned out to be a job for an AI agent rather than an app, at a fraction of the price. AI agents, explained for business owners covers when that works and when it doesn't.

Keeping MVP development cost down

The cheapest first version I've shipped cost exactly 9,000 €. It was for a linen and laundry service working for vacation rentals around Bandol, and only the landlords' orders went into the app at first, while the owner carried on doing the invoices from a spreadsheet and typing a monthly summary for each landlord on Sunday evenings. In June 2025 she told me she hated the Sundays. By September she had three months of it behind her and knew which half was worth automating, and the second phase came in under what I'd guessed in the spring.

Pendo, which tracks how its customers' products are used, went through its data in 2019 and found that 80 percent of features in the average software product are rarely or never used. The laundry app had no dashboard until a landlord asked her the same question twice, that October.

I test mockups on five people. Jakob Nielsen of the Nielsen Norman Group wrote in 2000 that a first test with five users finds about 85 percent of the usability problems, and on small apps I've found the same. At the Cassis estate it was four wine shop owners and a sommelier, at their own counters, and two of them couldn't find the confirm button.

CB Insights looked at 431 venture-backed startups that had shut down since 2023, and of the 385 whose reasons it could pin down, 43 percent had poor product-market fit. The median one had raised $11 million before finding out. The laundry service found out for 9,000 €.

Against a salary

Clients in the US sometimes ask me whether they'd be better off hiring their own developer than paying a one-person studio in the south of France. If the software is your main product and changes every week, I'd say yes. For everyone else the numbers look different. The US Bureau of Labor Statistics gives a median annual wage of $135,980 for software developers in May 2025, for one person over one year, before benefits and payroll tax, and a developer doesn't usually do the design or watch the servers on weekends.

Agencies are the other option. They put more people on a project and their day rate includes more overhead. On a large project the project manager earns that money, but on an app with one type of user and six screens much of it pays for meetings. Whether you need custom software at all, rather than a subscription, is a separate question, and I compared the two with real figures in the post on custom software for small businesses.

When you collect quotes, ask for them itemized like the 9,000 € one above, with the number of user types and integrations written on each, so you can see what moves the price. A few of the projects I've worked on are on the portfolio page.

If you'd like your own project broken down like that, book a 15-minute call.

FAQ

How much does custom software cost for a small business?

The wine estate in this article paid 9,400 €, the pool company 15,800 € and the marine electrics workshop 27,000 €. At Studio Calanque, custom web app development cost starts at 9,000 € before VAT, about $10,000, for one type of user, one process and one integration, built in four to eight weeks. Hosting and upkeep come to 100 to 300 € a month.

What does an MVP cost to build?

About the same as the smallest app, so from 9,000 € with me, as long as it really is one type of user and one process. The laundry service in Bandol stayed at that price because the owner did her invoicing by hand for the first three months.

Why do two quotes for the same app differ so much?

In Aubagne the 6,900 € quote was a form builder billed per technician, and the 58,000 € quote included iPhone and Android apps, a login for pool owners and twelve charts. They described different apps. Ask each provider how many user types and integrations their price covers and you can compare the two.

What does it cost to maintain custom software?

The pool company pays 160 € a month for hosting, backups, security updates and small fixes, and apps with one to three types of user usually cost 100 to 300 €. An app with no maintenance keeps running until a supplier changes its API.