Mobile App Development Agency

One Codebase.
Both App Stores.

We are the mobile app development agency US startup founders hire when the app has to ship on iOS and Android without doubling the budget. React Native, store submission handled, 99.9% crash-free — in about 10 weeks.

Audit My App Idea
Free Audit. Report in 48hrs.

shoparonline.com · USA Startups Only · Fixed Pricing

app_release.ts

const app = await buildMobileApp({

platforms: ['ios', 'android'],

codebases: 1,

crashes: 0

});

await app.submitToStores();

> Approved. Live on both stores.

10wks

Avg. mobile MVP to app store timeline

99.9%

Crash-free sessions target on client apps

100%

Source code ownership for every client

0

Projects abandoned mid-delivery

Mobile App Development Services

Native Feel. Startup Speed.

React Native development gives you one codebase, one team, and apps users cannot tell apart from native. Here is everything that ships with it.

iOS + Android, One Build

A single React Native codebase compiles to both platforms. Same features, same release day, half the engineering cost of two native teams.

Auth, Pay
& Push

The unglamorous 60% of every app: biometric login, Apple/Google Pay, subscriptions, push notifications that actually arrive, and offline mode. Done right, once.

Biometric auth
In-app purchases
Reliable push

Store Submission

App Store and Play Store listings, screenshots, privacy labels, and review compliance — handled for you, rejection risks flagged upfront.

OTA Updates

Over-the-air updates push fixes and improvements instantly — no waiting on App Store review for every iteration.

One Codebase
iOS & Android
99.9% Crash-Free
10-Week Delivery
One Codebase
iOS & Android
99.9% Crash-Free
10-Week Delivery
One Codebase
iOS & Android
99.9% Crash-Free
10-Week Delivery

Why Most Startup Apps Die.
And How We Fix That.

The app worked in the demo. Then real users installed it on real phones, Apple rejected the update, and the freelancer stopped answering. Sound familiar?

What Usually Happens

  • Two native codebases, double the cost, half the velocity.
  • App rejected by Apple review three times in a row.
  • Push notifications that never arrive. Users churn silently.
  • Crashes on 20% of Android devices you never tested.
  • Backend built for web, duct-taped onto mobile.
  • Freelancer shipped the demo, vanished before the App Store.

What saro Delivers

  • One React Native codebase. iOS and Android from day one.
  • App Store and Play Store submission handled for you.
  • Push, auth, payments, and offline mode engineered in.
  • Crash-free targets: 99.9% crash-free sessions or we fix it.
  • Backend APIs designed mobile-first, not adapted.
  • Over-the-air updates — ship fixes without App Store review.
How We Build Your App

4 Steps. No Surprises.

New app or rescue job, the process is identical. Fixed price, real builds on your phone every two weeks, and store submission handled end to end.

Step 01

Free App Audit

Have an app already? We audit it — crashes, store compliance, code quality, backend. Starting fresh? We scope the MVP. In 48 hours you get the full report with an exact fixed price.

Store rejection risks flagged before you submit
Step 02

Product Blueprint

Screens, user flows, API contracts, push strategy, and the store listing plan. You approve the blueprint before a single screen is built. No "we will figure it out in dev".

Clickable prototype before sprint 1 starts
Step 03

Agile Sprint Delivery

Your app ships in 2-week sprints with TestFlight and internal-track builds you can install on your own phone. You use the app while we build it.

Testable builds on your phone every 2 weeks
Step 04

Launch and Iterate

We handle App Store and Play Store submission, ASO basics, crash monitoring, and analytics. After launch, over-the-air updates keep you shipping without waiting on review queues.

99.9% crash-free sessions across client apps

Built for Founders
Going Mobile-First.

Your users live on their phones. Your MVP needs to be in the App Store, not in a Figma file. You are a non-technical founder who needs a mobile app development company that treats your launch date like a contract — because it is one.

saro builds your iOS and Android app from one codebase, handles both store submissions, and hands you the keys with documentation your next hire can read.

Book My Free Audit

Signs You Need a Real App Team

  • Your app idea has been "almost ready" for 6 months
  • A freelancer quoted two native apps at double the price
  • Apple rejected your submission and nobody knows why
  • Your app crashes on Android but works on iPhone
  • Push notifications arrive late — or never
  • Every update takes 3 weeks and a prayer
  • Investors asked "when is the app live?" and you dodged

Core Capabilities

Every service runs on the same engineering system. Pick what your startup needs.

Web Development

Fast, SEO-ready web apps for startups. Sub-second loads, fixed pricing, 6-week delivery.

View Web Development

MVP Development

Launch your startup MVP in 8 weeks on a real engineering system. Scalable, secure, and ready for customers.

View MVP Development

Software Rescue

Your app broke or stalled? We take over, kill the technical debt, and ship a stable build.

View Software Rescue Services

Common Questions.
Straight Answers.

What founders ask before they book. Answered directly, no fluff.

What does a mobile app development agency do?
A mobile app development agency designs, builds, tests, and launches your iOS and Android app — plus the backend APIs it runs on. That includes product strategy, UI design, native-quality engineering, App Store and Play Store submission, push notifications, analytics, and post-launch updates. saro builds startup mobile apps in React Native, so one codebase ships to both stores in about 10 weeks.
How much does it cost to build a mobile app for a startup?
A startup MVP app typically costs between $15,000 and $40,000 depending on scope — user accounts, payments, real-time features, and admin tooling drive the price. Building separate native iOS and Android apps roughly doubles that. saro uses React Native for one codebase across both platforms and works on fixed pricing: exact quote in the free audit, price never moves.
Should I build native iOS/Android or use React Native?
For 95% of startups, React Native. You get one codebase, one team, and near-native performance for a fraction of the cost and time. Pure native makes sense only for graphics-heavy games, AR, or deep hardware integration. We will tell you honestly if your app is in the 5% — most are not.
How long does mobile app development take?
A focused MVP — onboarding, core feature set, payments, push — takes 8 to 12 weeks on our sprint system. App Store review adds 1 to 7 days on top. If you have an existing app that needs rescue, stabilisation takes 4 to 6 weeks before new features ship.
Can saro fix my existing app or get it approved by the App Store?
Yes. We audit the app for crashes, store guideline violations, and backend issues, then give you a fixed-price rescue plan. We have handled Apple review rejections, broken push infrastructure, and Android fragmentation crashes. The audit identifies every blocker before you commit.
Do I own the app and the source code?
Completely. You own 100% of the source code, the App Store and Play Store listings are in your developer accounts, and all backend infrastructure is in your name. We hand over everything with documentation. No hostage situations.
Free 30-Minute Audit

Get Your App
In Their Hands.

We audit your app idea — or your existing app — and give you a clear path to both app stores in 48 hours. Exact scope. Exact cost. No retainer. No BS.

saro is the mobile app development agency USA startup founders call when the app has to ship. Book the call. We tell you exactly what it costs.

Book a Free App Audit

shoparonline.com · USA Startups Only · Report in 48hrs