Ask three agencies how long custom software takes and you’ll get the same answer three times over: it depends. True, but not much use to you. So here’s an honest range first, across the full breadth of custom development. A well-defined internal tool is ready within a few weeks. Most business applications need several months. A system spanning multiple departments, user groups and external integrations can stretch towards a year.
That range exists because of a handful of factors. This article covers those factors and how you can influence them yourself, whatever kind of custom software you’re having built. If you’re specifically after a web application or portal and want to see that route stage by stage, read the timeline for a web application, from first conversation to launch. Knowing the factors also means you’ll spot a schedule that’s too good to be true.
The size of the challenge sets the timeline
The timeline doesn’t come from the agency’s diary, but from what you’re having developed. Four factors weigh heaviest:
- the number of processes the application supports, and especially the number of exceptions within those processes
- the integrations with existing systems, such as your accounting software, CRM or planning tools
- the number of user types, each with their own screens and permissions
- the security and privacy requirements, especially when personal data is involved
Of these four, integrations with other systems are underestimated most often. Every connection needs development and testing, but also coordination with an external party: requesting documentation, arranging access, waiting for a reply. That waiting is exactly what optimistic schedules never account for.
Working software doesn’t have to wait until everything is finished
A project that runs for months doesn’t mean you spend months staring at a progress report. We develop in short cycles and put the functionality that delivers the most value first. That way, a first working version is ready within a few weeks, already carrying part of the workload, while the rest is built out in stages.
That shifts the question from when everything will be finished to when your organisation actually benefits from it. For budget, planning and bringing your people along, that second moment usually matters most. The total project doesn’t get shorter because of it, but the time to first result does.
Where the time actually goes
Most time doesn’t go into typing code, but into understanding: how your processes run, where the exceptions sit, what should happen when an order gets cancelled halfway through. After that it goes into testing, because the exception nobody mentioned is guaranteed to turn up in production.
We develop AI-assisted ourselves, and it’s noticeably sped up the writing of code. It doesn’t speed up the conversations about what the software needs to do, and those are exactly what determine whether the result is right. So be wary of a supplier who mainly promises speed: that’s usually the understanding they skimp on.
Delays rarely come from the technology
Projects mostly overrun because of things outside the code. Wishes that get added along the way without anything being dropped. Decisions that wait weeks for sign-off. Stakeholders who have no time to review interim versions. You can do something about all three yourself.
Appoint one decision-maker who can make the final call. Block out time at the start with the people who’ll be working with the software, so feedback doesn’t get stuck. And be strict about scope: new wishes are welcome, but they get a slot in a later phase rather than in the current schedule. For more on preparation, read the questions to ask before you have software developed.
If you want a timeline for your own situation, a conversation is faster than a calculation model. We develop custom applications from Amsterdam, and in a first conversation we’ll sketch which route fits your challenge and what timeline is realistic for it. Even when the honest answer is that off-the-shelf software gets you there faster, you’ll hear that from us.