How long does it take to build an app or custom software?
A couple of days for a tiny tool, about a week for something basic, a couple of months for a proper business system, and up to a year when the stakes are high. Andrei on what moves those numbers.
It depends on what you're building, so here's how I think about it in four sizes. These are rough build times once the scope is clear.
A very small tool, something really minor, could probably be built by the person themselves in a couple of days. Think of the quick calculator or the one-off helper I talked about in question 8.
Something a little bigger, with very basic functionality or a few basic integrations, takes maybe half a week to a week. A form that saves to a database and sends an email is the kind of thing I mean.
Something more nuanced and in depth takes two to three months. This is where you have real business logic, different kinds of users, and more integrations. It's also where the edge cases start to bite, which is the 80/20 rule I mentioned earlier.
And then there's the really heavy stuff, where there's a lot of testing involved and it's critical that every bug is ironed out before it goes live. You're dealing with financials, things like that. That can take six to twelve months, and a lot of that time isn't writing code. It's testing, security checks and making sure it does exactly what it should every time.
A few things move those numbers around. How clear the scope is, for a start. How many other systems it has to connect to, and how well they behave. Whether your data has to be migrated out of spreadsheets or an old system first. How quickly you can give feedback and make decisions, because waiting on answers adds up fast. And how much testing the stakes demand.
AI has helped with building and testing, as I said earlier. But the edge cases and the decisions still take the time, so don't expect AI to turn months into days for anything that matters.
There are ways to shorten it. Start with a small first version that does the main job, get it live, and add to it. Have one person who can make decisions. Write down what done looks like before we start. And build on a clean slate where you can, because migrations add time.
So the honest answer is a couple of days for a tiny tool, about a week for something basic, a couple of months for a proper business system, and up to a year when the stakes are high.
