What does custom software actually cost?
The short answer
Most of the cost of custom software is decision-making, not typing. The price is driven by how many distinct workflows it covers, how many systems it has to talk to, and how much ambiguity is left when the build starts — not by the number of screens. A narrow, well-defined first version is usually a fraction of what people expect, because the expensive part is scope, and a first version deliberately has very little of it.
Why nobody will give you a number on the phone
Because the honest answer to “what does custom software cost?” is the same as “what does a building cost?” — and anyone who answers instantly is either quoting their cheapest past project or about to be wrong.
What we can tell you is what actually moves the number.
The four things that drive the price
1. How many distinct workflows it covers
Not screens. Workflows. A system that does one thing end to end — take a booking, take payment, send a confirmation — is a small build. A system that also handles refunds, group bookings, partial payments, reschedules and an admin override is four more workflows, each with its own edge cases.
This is the single biggest lever you control.
2. How many other systems it has to talk to
Every integration is a negotiation with someone else’s software. A clean, documented API is a day. An accounting system with a 2009 SOAP interface and no sandbox is a fortnight. A system with no API at all, where data has to move by scheduled file export, is a project of its own.
Ask early: what does this have to connect to, and does that thing have an API?
3. How much ambiguity is left at the start
This is the cost nobody budgets for. If the business genuinely does not know what should happen when a customer cancels after the cut-off, that decision will get made during the build — usually two or three times, each time undoing work.
Discovery is not a consultancy upsell. It is the cheapest place to make decisions.
4. Data migration
Getting ten years of records out of the old system, deduplicated, reconciled and loaded is routinely underestimated. The data is always messier than anyone remembers.
What a first version actually costs
Much less than the full system, which is the entire point of building one.
A first version should cover a single workflow, on real data, for a real group of users. It is deliberately missing things. It exists to answer one question: does this actually help, and do people use it?
At ShiftedLabs we start almost every project this way. If the prototype is disappointing, you have learned something valuable for a fraction of the full budget. If it works, the rest of the build is far better informed — and you are no longer buying on faith.
The running costs nobody mentions
A custom system is not a one-off purchase. Budget for:
- Hosting. Often trivial. Most systems we build run on Netlify and Supabase for a few euros a month. Scale changes this, but far later than people fear.
- Third-party services. Payment processing, email delivery, verification, SMS. These are per-use and scale with the business, which is the right shape.
- AI calls, if the system uses a model. This one genuinely can run away from you if nobody caps it. Every AI call we build is cached and capped for exactly this reason.
- Maintenance. Dependencies age, APIs change, browsers move. Something that is never touched for two years is not free, it is accruing a debt.
Where custom software is cheaper than SaaS
Per-seat pricing is the usual reason. A £40-per-user-per-month tool across 40 people is £19,200 a year, every year, forever. Custom software has a higher upfront cost and a much lower marginal one — the tenth user and the hundredth cost about the same.
The crossover point arrives sooner than most people expect, particularly when the custom system replaces three subscriptions rather than one.
Where it is not
If your process is genuinely standard, buy the standard tool. Off-the-shelf software is cheaper, better supported and immediately available. We say this to prospective clients regularly, and it costs us work.
Custom software earns its keep when your data is unusual, when keeping it current is somebody’s manual job, or when one process is currently stretched across three products that do not share data.
How to get a useful estimate
Come with the problem, not the specification. “We need a booking system” prices badly. “Customers phone us during office hours to change bookings, and it takes about fifteen hours a week across two people” prices well — and often turns out to need something smaller than a booking system.