How much does it cost to build an app like Duolingo?

There is no one figure, because "an app like Duolingo" covers three very different builds: a first version with only the essential features, a complete and credible competitor, and a rebuild of everything the mature product does at the traffic it carries. Those are several-fold apart. What this page gives you is the shape of each — the sides, the feature tiers, the stack and the compliance — and the calculator turns whichever one you actually mean into a cost range, hours and a timeline.

Because it is not one app. It is 3 separate applications — learner app, course authoring tools, experimentation platform — sharing one backend, each with its own design, release cycle and test matrix. Most quotes that come in low have counted one of them. Retention mechanics are real engineering: Streaks, leagues, hearts and reward loops need consistent state across devices and time zones, integrity against manipulation, and constant experimentation. They are not UI polish; they are the product's core systems.

Yes, and you should. A first version ships the essential feature tier rather than all three, on fewer surfaces, at a launch-sized audience — materially less than the full product, and the calculator will show you by how much. What it does not cut is compliance: education obligations apply from the first user, so those stay in whatever else is deferred.

It depends on the same three things the cost does — which tier of the product you mean, how many surfaces you ship, and how settled the scope is. The calculator returns a timeline alongside the cost, derived the same way: hours divided across a realistic team shape, never a target date worked backwards from.

Cloud infrastructure, third-party services and annual maintenance, and the calculator reports all three separately from the build. They are kept out of the build figure deliberately: they are operating expenditure rather than capital, and adding the two together produces a number that means nothing. Maintenance in particular is not optional — an app that receives none stops working within about a year as OS releases and SDK deprecations accumulate.

This page carries no figures at all, and nobody outside the company has real ones. What it describes is the product SHAPE, observed from what any user can see — the sides, the feature tiers, the stack, the compliance. Nothing here describes what Duolingo actually spent, earns, employs or runs on. The calculator prices building something of that shape today, for the United States market, at our own blended delivery rate.

FERPA applies if you handle student education records on behalf of a US school. COPPA applies if any user is under 13, and it is the more consequential of the two: it requires verifiable parental consent and restricts data collection and advertising outright, which changes your product and business model rather than adding a checkbox. Determine which applies before you design signup, because retrofitting consent flows is expensive and sometimes requires re-onboarding your existing users.

It is a planning estimate, not a quote. The band shown is roughly plus or minus 15–20% for a well-defined scope, and wider while requirements are still moving. It is built from engineering hours per discipline, converted at our blended delivery rate, so the hours are directly comparable to a real proposal line by line — but a firm price needs a technical specification, which is the step after budgeting.