Mobile Apps Shipped Sprint by Sprint, Tested on Real Devices
SprintOne Labs builds iOS and Android apps in two-week sprints, each ending with a build tested on real devices, and sells mobile app development services to startups, SaaS and consumer companies: native Swift and Kotlin, cross-platform Flutter and React Native, plus backend and APIs. That rhythm defines our custom mobile app development services: app updates ship fast without regressions, since QA sits inside the sprint and autotests run on every build. Mobile application development starts as a fixed-scope app build or as engineers added to your team; request a scoped estimate for either.
Every Sprint Ends With a Build on Real Devices
Nothing counts as finished until it runs on a phone. Simulators hide the faults users meet first: slow launches, broken gestures, layouts cut off by a notch. So each sprint closes with an installable build, checked on hardware, with the evidence attached to the ticket.
The device list comes from your analytics. We read which models and OS versions your audience holds. The most common ones sit on our desks as physical iPhones and Android handsets. A cloud device farm reaches the long tail. That is how device fragmentation gets handled without guessing.
On every build, automatically:
- Unit tests for business logic
- API tests against the backend the app calls
- UI autotests through the main user journeys
Once per sprint, by hand:
- Exploratory sessions on new screens
- Gestures: swipe, pinch, long press, back navigation
- Interruptions: an incoming call, low battery, a poor network, no network at all
- Offline mode and the sync that follows reconnection
Ahead of the sprint demo: performance and battery checks. Cold start is timed. Memory use is watched during long sessions. Battery drain is compared with the previous build, so a regression has a date and a commit. App security basics get a pass too: token storage, encrypted transport, the permissions the app requests.
Ahead of a store release: a pre-submission checklist against the App Store Review Guidelines and Google Play policies. It runs for each submission, not only the first one. Most rejections trace back to plain causes. A reviewer cannot log in. A privacy disclosure is missing. A purchase flow skips the store's billing rules. A link leads nowhere. Each of those is a checklist line, and each gets ticked on a device before upload.
The result: >97% of critical defects are found before release. For a SaaS team releasing every two weeks, the mobile update then leaves on the same day as the web one. The rule also keeps our custom mobile app development services honest. A sprint without a tested build is visible to you at once.
What Is Mobile App Development?
Mobile app development is the process of designing, building, testing and releasing software applications for iOS and Android phones and tablets, together with the backend they rely on: servers, APIs, databases and third-party integrations. It runs from the first wireframes to store submission and continues with updates after launch.
Apps come in a few technical shapes. A native app is written separately for each platform. A cross-platform app shares one codebase between both. A hybrid app wraps web content in a native shell. A progressive web app skips the stores and lives in the browser.
A service engagement covers more than code. Typical mobile development services include:
- Discovery and platform choice
- UI/UX design, wireframes and a clickable prototype
- iOS, Android or cross-platform engineering
- Backend and API work
- QA and testing on devices
- Store submission, analytics setup and post-launch maintenance
Some things stay on your side. You bring the Apple Developer and Google Play Console accounts, registered to your company. You bring brand assets: logo, colors, fonts, tone. You bring content, legal texts and one person who can make product decisions each sprint. Without that person, a two-week cycle stalls on unanswered questions.
What We Build for iOS and Android
Seven kinds of work follow, each closed by its own test. Order one, or combine several into a single sprint plan.
iOS App Development (Swift)
Our iOS app development services deliver native Swift apps for iPhone and iPad, with push notifications, in-app purchases and widgets where the product needs them. Tested: each TestFlight build runs on physical iPhones across the supported iOS versions.
Android App Development (Kotlin)
Android app development services here mean native Kotlin, shaped for the screen sizes and manufacturers your audience uses. Background work, permissions and battery limits are handled per OS version. Tested: internal-track builds go onto real handsets, and the farm reaches rare models.
Cross-Platform Apps (Flutter, React Native)
One codebase serves both stores. Our cross platform app development services span Flutter app development services and React Native app development services, with native modules written when a device feature demands one. Tested: the same UI suite executes on both platforms per build.
App UI/UX Design & Prototyping
Wireframes come first, then a clickable prototype you tap through on your own phone. This is the design half of our mobile app design and development services. Tested: prototype flows are walked with stakeholders before a sprint is spent coding them.
MVP App Development for Startups
A first version carries only the flows that prove the idea. As an MVP app development company, we cut scope in Sprint 0, not after the budget is gone. Tested: even the smallest release passes crash and cold-start checks.
Backend, API & Integrations for Mobile
Apps need accounts, payments, analytics and data sync. Those services come from our software development team, and AI features in apps are added when they earn a place. Tested: contract and load tests hit each endpoint ahead of the app's UI.
App Modernization, Takeover & Maintenance
Older apps get audited, stabilized and moved to current OS releases. Maintenance and updates then follow the usual two-week rhythm. Tested: a regression suite is written around existing behavior before any refactoring begins.
Native or Cross-Platform? How We Decide
Platform choice is a product decision before it is a technical one. Native code gives the fullest access to the device and the smoothest rendering. Cross-platform code gives one team and one release train for both stores. Hybrid sits apart: it suits content-heavy products with light device needs, and the hybrid app development company route rarely fits anything animation-heavy.
| Criteria | Native (Swift/Kotlin) | Cross-platform (Flutter/React Native) |
|---|---|---|
| Performance | Highest ceiling for graphics, video and heavy computation | Close to native on most business and consumer screens |
| Device features | New OS APIs usable as soon as Apple or Google ship them | Most features through plugins; some need a native module |
| Time-to-market | Two codebases moving on parallel tracks | One codebase and one sprint backlog for both stores |
| Budget | Higher, because most features are written twice | Lower for an equal feature set on both platforms |
| Team you already have | Fits if you employ Swift or Kotlin developers | Fits if your people know Dart, JavaScript or TypeScript |
Native usually wins for:
- Games, video editing and augmented reality
- Apps built around Bluetooth, sensors or background location
- Products that must adopt new OS features at launch
Cross-platform usually wins for:
- Marketplaces, booking, banking front ends and internal tools
- Startups that need both stores from one budget
- Teams with web engineers ready to move to mobile
Our rule of thumb: go cross-platform unless a named feature needs native. Name that feature in Sprint 0. As a custom mobile app development company, we write the choice into the results criteria before development begins. After that it cannot drift mid-project.
Our Sprint Calendar: From Sprint 0 to Store Release
Dates replace phases in our plan. Mobile application development here runs on a calendar you can read without us in the room.
- Sprint 0, week 1: Discovery and platform choice. We map users, core flows and the systems the app must talk to. Native or cross-platform gets settled in the same week. You leave it with a ranked feature list.
- Sprint 0, week 2: Results criteria in writing. One document fixes the feature list, the crash-free target, the performance budget and the supported OS versions and devices. Defaults are crash-free sessions ≥99.5% and cold start ≤2 s, unless you set others. Both sides sign before any code exists.
- Sprint 0 into Sprint 1: UI/UX design and clickable prototype. Designers turn wireframes into screens and link them into a prototype. You try it on a phone and mark what feels wrong. A change costs minutes at this stage instead of days later.
- Sprint 1 onward: Development with QA in the same sprint. Developers and QA engineers pick up the same stories on the same morning. The pipeline is wired first, so autotests run on every build from the start. Sprint 1 ends with the first TestFlight and internal-track build on your device, and each following sprint adds a tested increment.
- Release sprint: Regression, store checks, submission. Full regression runs beside performance, battery and offline tests. The build is compared with both stores' review guidelines, then submitted to the App Store and Google Play. Listing texts and screenshots get a basic app store optimization pass.
- After release: Crash monitoring, OS updates, backlog. Crash reports and analytics feed the next sprint's plan. New iOS and Android versions are tested against while still in beta. Then the calendar continues at whatever pace your roadmap needs.
Inside a feature sprint, the two weeks have a fixed shape:
- Week 1, start: planning, story breakdown, test cases drafted beside the stories
- Week 1, rest: coding and testing in parallel; builds flow to the internal track daily
- Week 2, first half: remaining stories, exploratory sessions on devices, defect fixes
- Week 2, close: performance and battery pass, demo on hardware, build handed to you
Agile sprints stay honest when the demo happens on a phone. A slide cannot crash. A build can, and we would rather see it crash on our desk.
Mobile App Development Cost by App Type
Budgets depend first on what kind of app you are building. The table gives the typical US market range per type. These are market figures for context, not our quotes.
| App type | Typical scope | Typical US market range | Timeline |
|---|---|---|---|
| MVP / single-platform app | One platform, core flows, simple backend | $25k–$80k | 2–4 months |
| Mid-complexity app | Both platforms, backend, payments | $80k–$250k | 4–8 months |
| Complex / enterprise app | Real-time features, offline sync, integrations, compliance | $250k+ | 8–12+ months |
| Design-only engagement | UX research, wireframes, UI, prototype | $8k–$30k | Set by scope |
Five drivers move a project inside its range:
- Platforms. iOS app development cost and Android cost are similar per platform. The second platform is what raises the bill.
- Backend complexity. A login and a feed are light. Real-time messaging and offline sync are not.
- Integrations. Payments, maps, CRM and analytics each add build and test time.
- Custom UI. Standard components are fast. Bespoke animation takes design and tuning on devices.
- Compliance. Health or payment data brings extra reviews, documentation and security testing.
As a market norm, plan maintenance at about 15–20% of the build cost per year. That covers OS releases, library updates and store policy changes.
Our own numbers work per sprint. Put 1 Swift, Kotlin or Flutter developer on your app for 80 h at $65–75/h. Add a device tester for 40 h at $40–45/h, which is half allocation. Those two weeks of app work total about $6,800–$7,800. An automation engineer for the app's regression suite bills at $45–55/h. Multiply by the sprints on your calendar and the build budget appears. Final rates shift with seniority, stack and time-zone overlap. Our app development services carry no minimum project, so a single sprint is a valid order.
Ways to Work With Us
Ownership of the backlog decides the format. Either we own delivery of a defined app, or your lead directs our people, or we inherit something already live.
Fixed-Scope App Build
You have a defined app and want it delivered. Scope, acceptance criteria and milestones are written down in Sprint 0. Each milestone is a build you install and accept on a device. Invoices follow accepted milestones, so progress and payment stay tied together.
Mobile Engineers in Your Team
You have a team and a gap in it. iOS, Android or Flutter developers and mobile QA engineers join your sprints and tools within 3–5 business days. They report to your lead and work in your tracker. Headcount moves up or down without re-signing the contract. The staff augmentation page lists the terms.
Takeover & Maintenance of an Existing App
You have an app and nobody to look after it. An audit comes first: code, crash data, store status, test coverage. Then we stabilize the app, wrap regression tests around it and settle into a release rhythm.
Across all formats, the code, the store accounts and the IP belong to you. Repositories sit under your organization, and an NDA is signed before discovery. A custom mobile app development company should be replaceable. We keep it that way on purpose.
Why SprintOne Labs
Speed is easy to promise and hard to keep once an app has users. These four habits are how we keep it, as an iOS app development company and an Android app development company in one team.
QA in Every Sprint, on Real Devices
A testable build lands on real devices at the close of every sprint, so app updates ship fast without regressions. By release day, >97% of critical defects are already found. Your store rating is never the test environment.
Acceptance Criteria Before Code
Crash-free rate, performance budget and OS coverage are agreed in writing first. Each build is judged against that document, not against hours logged. One engineer on our team is ISTQB-certified and reviews how those app criteria get tested.
Direct Contact With the Engineers
A shared channel connects you to the developers and testers of your app. Ask about a crash, and whoever fixed it replies. Nothing is filtered through an account manager.
Mobile Engineers Within 3–5 Business Days
An extra Kotlin developer or device tester joins your sprints in 3–5 business days. They are based in Eastern Europe, with at least 4 hours of overlap with US Eastern. Capacity follows the roadmap instead of the contract.
Technologies & Tools We Use for Mobile
Every build passes through one pipeline before a person touches it. GitHub Actions compiles the app and starts the checks. Tests for the backend, the admin panel and any web companion run in Playwright + TypeScript or Cypress. They execute inside Docker containers, so a result on one machine matches the next. Allure collects the reports, with a screenshot beside each failed step. That is our CI/CD for mobile in four words: commit, build, test, report.
The product stack is picked per project. On the device: Swift, Kotlin, Flutter or React Native. Behind it: Node.js, .NET or Python on AWS, Azure or GCP. Teams that come for Flutter app development services get the identical pipeline as native projects.
Free QA Audit in 2–3 business days
Before any estimate, we check your app's release cycle at no charge. The audit works for a live app or one still in development. Here is what gets examined:
- QA process: how an app change travels from ticket to store release
- Critical flows: sign-up, login, payment, and whether tests cover them
- Existing test cases for the app, and the screens they skip
- Automation: what runs today, on which builds, and how well it catches defects
- Next candidates for automation, ranked by regression effort removed
Then you get a short audit report listing findings, risks and recommendations for the app. Once we hold a build, repository access and product info, the app report takes 2–3 business days. No commitment is attached. An e-commerce checkout before peak season is a typical subject: one flow, one deadline, one clear list of what could break it. Hand the report to your current app team, or request an estimate from us.
FAQ
How much does it cost to develop a mobile app?
Developing a mobile app costs $25k–$80k for an MVP on one platform and $80k–$250k for a mid-complexity app on both, as a typical US market range. Complex or enterprise apps start at $250k. SprintOne Labs prices by sprint: about $6,800–$7,800 buys two weeks of one developer plus half-time QA on devices.
How long does it take to build a mobile app?
Building a mobile app takes 2–4 months for an MVP, 4–8 months for a mid-complexity product and 8–12+ months for a complex one, by typical market timelines. Our calendar makes progress visible sooner. Sprint 1 already produces an installable build, and each later sprint adds an increment you can show to users or investors.
Should we build native or cross-platform?
Build cross-platform unless a specific feature requires native code. Flutter and React Native handle most product screens with a shared codebase and a single release schedule. Swift and Kotlin win when the app leans on heavy graphics, brand-new OS capabilities or deep hardware access. We settle the question in Sprint 0 and record it in the written criteria.
How do you test the app before it goes to the App Store or Google Play?
We test each release candidate on physical iOS and Android devices, then on a cloud farm for less common models. Automated unit, API and UI suites must pass first. Manual sessions follow for gestures, interruptions and offline behavior. Last comes a review-guideline checklist for both stores, which removes known rejection reasons before anyone presses submit.
What is mobile app development?
Mobile app development means creating software for phones and tablets, from design through coding, testing and store release. The server side belongs to it as well: APIs, databases and integrations the app calls. A full engagement also covers life after launch, such as OS-version updates, crash fixes and new features delivered in regular sprints.
Can you take over an app built by another vendor?
Yes, we take over existing apps, starting with an audit instead of a rewrite. We read the code, the crash history and the store status, then list what is risky. Regression tests go in around current behavior next. After that, fixes and features move into two-week sprints, and urgent patches stop waiting for a big release.
Who owns the app, the code and the store listings?
You own all of it: source code, designs, store listings and every other piece of IP. Repositories are created under your organization, and the Apple and Google developer accounts are registered to your company. Our engineers work as invited members. An NDA is in place before discovery, and you can withdraw access on any day.