Mobile App Development

Long Island App Developer

Native-quality iOS and Android apps, built by one engineer who designs, codes, and ships the whole thing — fast, polished, and made to last on the App Store and Google Play.

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I’m Ken Key, a Long Island app developer who builds mobile apps end to end — from the first sketch to a live listing on the App Store and Google Play. Most apps fail not because the idea was wrong, but because they were assembled by a rotating cast of contractors with no one accountable for how the whole thing felt. I work the opposite way: one engineer who designs it, codes it, and ships it.

I build cross-platform with React Native and Expo so a single, well-engineered codebase runs natively on both iOS and Android — and I reach for native Swift when a project genuinely calls for it. Push notifications, in-app purchases, sign-in, real backends and APIs — wired in properly, not bolted on. It’s the same way I build the apps behind KeyInventions. Whether you’re a Long Island business that needs an app or a founder with an idea and no technical co-founder, you get something that feels native, loads fast, and you’re proud to put in someone’s hand.

What you get

What an app build includes

iOS & Android from one codebase

React Native and Expo for a single, maintainable codebase that runs natively on both stores — plus native Swift when a project demands it.

Designed and built by one person

No agency handoffs or lost-in-translation specs. The person who designs your app is the one who codes and ships it.

Push, payments & real backends

Notifications, in-app purchases, authentication, and APIs built in properly — the parts that make an app actually useful.

Launched, not just built

App Store and Google Play submission, review, and the ongoing updates that keep an app alive as the OS moves under it.

How it works

A simple, honest process.

01

Understand

We talk through what you’re actually trying to achieve. If I’m not the right fit, I’ll say so and point you somewhere better.

02

Build

I design and build it properly, keep you in the loop, and make the trade-offs visible instead of hiding them.

03

Last

You get something fast, documented, and maintainable — and I’m here when you need to grow it.

Good questions

Frequently asked.

How much does it cost to build an app?

It depends entirely on scope — a focused MVP is a very different project from a full platform with accounts, payments, and a backend. After a short conversation about what you actually need, I’ll give you an honest, fixed range. No padded retainers.

iOS, Android, or both?

Both, usually from one codebase. I build cross-platform with React Native / Expo so a single build ships to the App Store and Google Play — which keeps cost and maintenance down. When a project needs deep native iOS work, I build in Swift.

Can you take my app from idea to the App Store?

Yes — that’s exactly the kind of work I like most. Idea, design, build, store submission, and launch, with one engineer accountable for the whole thing.

Do you maintain apps after launch?

Yes. Apps aren’t “done” at launch — iOS and Android change every year. I keep apps current, fix issues, and add features as you grow.

Related

Explore more of what I do

Serving Long Island

Working across Suffolk & Nassau.

Based in Commack and working with businesses all over Long Island — and remotely beyond. If you searched “app developer near me,” you’re in the right place.

Commack Huntington Smithtown Hauppauge Melville Babylon Islip Northport Suffolk County Nassau County

Have an app idea worth building?

A few sentences about your project is all it takes to start.