Expect BestPicking a mobile app developer often comes down to one question: which languages should they actually know in 2026? The honest answer is that the language matters less than the fit between the tool and the job. A good developer chooses the stack that suits your product, your budget and the platforms your customers use. Still, it helps to know the main options, so here is a plain guide to the languages and frameworks behind well-built apps, and what each one signals about the person writing your code.
1. Swift for native iOS
Swift is Apple's modern language for iPhone and iPad apps. It replaced Objective-C as the default several years ago, and it is now what you should expect for any serious native iOS work. Swift is fast, safe by design, and pairs with SwiftUI for building interfaces. If a developer still leads with Objective-C for a brand new project, treat it as a warning sign: the language is fine for maintaining older apps, but it is not where new iOS development happens.
2. Kotlin for native Android
Kotlin is Google's preferred language for Android, and it has largely taken over from Java for new builds. It is cleaner to read, less prone to certain common bugs, and fully supported by Android's official tools. Java still turns up in plenty of existing Android apps, so a strong Android developer will be comfortable with both. For anything new, though, Kotlin is the sensible default.
3. Dart and Flutter for cross-platform
Flutter, built on the Dart language, lets a team build for iOS and Android from a single codebase. It has become one of the most popular ways to ship on both platforms without writing everything twice. The appeal is obvious: one team, one codebase, and a consistent look across devices. The trade-off is that very hardware-specific features, or designs that must match each platform exactly, can need extra native work. For many mobile app projects, Flutter hits a good balance of speed and quality.
4. JavaScript, TypeScript and React Native
React Native uses JavaScript, and increasingly TypeScript, to build cross-platform apps. It is a natural fit for teams that already work in JavaScript on the web, because a lot of knowledge and code carries across. TypeScript adds a layer of type checking that catches mistakes before they reach your users, which is why most serious teams now prefer it over plain JavaScript. If your project also involves a website or a web app, sharing skills across both can keep costs down and delivery faster.
5. The language behind the scenes
Most apps are only half the story. The other half is the server that stores data, handles logins and connects to payment or booking systems. This is where languages like JavaScript on Node.js, Python, PHP or C# come in. If your app needs accounts, a database or anything that syncs between devices, your developer needs to be comfortable building and securing that back end too. This work often overlaps with web development and custom systems, so it is worth checking your developer can handle both sides.
What actually matters when you hire
Languages are tools, not goals. A developer who reaches for the same stack regardless of the brief is a bigger risk than one who asks what your app needs to do first. Look for someone who can explain, in plain terms, why they would build your app natively or cross-platform, how they will handle updates on both app stores, and what happens to your code if you part ways later. Ask to see work they have shipped, and ideally apps that are still live and maintained.
It also helps to think past launch day. An app needs updates as iOS and Android change, and the language and framework you start with affect how easily that happens. A cross-platform choice can lower the cost of maintaining two versions, while a native build can be the right call when performance or platform features are central. For more on that decision, our guide to cross-platform app design weighs up the trade-offs.
If you are weighing up an app for your business and want a straight answer on the right approach, we are happy to help. Get in touch and we will talk through what your idea needs, without the jargon.
