Mobile app developer

What does a mobile app developer do?

A mobile app developer builds and maintains apps for phones and tablets.

You write code for iOS, Android or both, test it on real devices, and publish it through the App Store and Google Play.

In Singapore, the role sits in product or engineering teams at banks, government agencies, telcos, logistics firms, startups and agencies. Some developers work on consumer apps. Others build internal tools for staff.

You work with product managers, designers, backend developers and QA engineers. You also deal with security and compliance teams when an app handles personal or financial data.

What the work involves

• Turn designs and requirements into screens and features in Swift, Kotlin, Flutter or React Native.
• Connect the app to backend services through APIs and handle errors, slow networks and offline use.
• Test builds on different phones and operating system versions, and fix crashes and layout faults.
• Review teammates' code in Git and agree on how to split work across releases.
• Prepare builds for release, answer store review feedback, and watch crash reports and user reviews after launch.

Pay in Singapore

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Skills a mobile app developer needs

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Mobile app developer job description

We are looking for a mobile app developer to build and maintain apps used by customers or staff in Singapore.

You will work in a small product team, write and test code for iOS, Android or both, and take features from design to store release. You will work closely with designers, backend developers and QA engineers.

Responsibilities

• Build app features from product requirements and design files.
• Write clean, tested code in Swift, Kotlin, Flutter or React Native.
• Integrate the app with REST or GraphQL APIs and backend services such as Firebase or Supabase.
• Store user data safely on the device and handle sign-in and session tokens with care.
• Test on real devices and fix performance, crash and compatibility issues.
• Review code from other developers and keep work organised in Git.
• Prepare builds, signing and store listings, and manage releases to the App Store and Google Play.
• Monitor crash reports, analytics and user reviews, and plan fixes.
• Follow the organisation's security and data protection rules, including the Personal Data Protection Act (PDPA).
• Document how the app is built so other developers can pick it up.

Requirements

• Diploma or degree in computer science, information technology or a related field, or equivalent practical experience with a portfolio.
• Typically 1 to 3 years of experience building mobile apps; entry-level roles accept graduates with internship or personal projects.
• Working skill in at least one of Swift, Kotlin, Flutter or React Native, and an understanding of how iOS and Android differ.
• Experience calling APIs, handling JSON data and using Git in a team.
• At least one app published, or a build you can demonstrate on a device.
• Familiarity with Firebase or Supabase is often asked for, especially in startups.

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Mobile app developer career path

Most mobile developers start on a single platform, then widen to cross-platform work or the backend.

From there, you can lead a squad or move into management.

1. Junior mobile developer

   Entry

   You build small features and fix bugs under guidance, and learn the team's code and release steps.

2. Mobile app developer

   Mid

   You own features from design to release, work with backend teams on APIs, and review others' code.

3. Senior mobile developer

   Senior

   You make design choices for the app, deal with performance and security problems, and guide less experienced developers.

4. Mobile tech lead

   Lead

   You set technical direction for one or more apps, plan work with product managers and coach the team.

5. Head of mobile or engineering manager

   Head

   You manage mobile teams, hiring and budgets, and decide how the organisation builds and releases its apps.

The titles are ones commonly used in Singapore; employers may name the levels differently.

Related jobs and their pay

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Mobile app developer interview questions

We wrote these questions from the skills this job needs. They are not an official question bank.

1. When would you choose Swift and Kotlin over Flutter or React Native for a new app?

   What a good answer covers

   • Names cases for native: heavy use of device features, graphics, or platform-specific design.
   • Names cases for cross-platform: one small team, shared logic, faster delivery on both stores.
   • Mentions team skills and long-term maintenance cost.
   • Admits that plugins and OS updates can break cross-platform apps.

2. How would you design an app so users can still view and edit data with no network?

   What a good answer covers

   • Stores data in a local database such as Core Data, Room or SQLite.
   • Queues changes and syncs them when the connection returns.
   • Explains how to handle conflicts, such as last-write-wins or merge rules.
   • Shows the user clear status, such as pending or failed sync.
   • Tests with airplane mode and a weak connection.

3. How do you handle login tokens and API keys safely in a mobile app?

   What a good answer covers

   • Keeps tokens in the Keychain or Android Keystore, not in plain preferences.
   • Uses short-lived access tokens with refresh tokens.
   • Explains that secrets in the app bundle can be extracted, so sensitive keys stay on the server.
   • Uses HTTPS and mentions certificate pinning for high-risk apps.
   • Clears data on logout.

4. Walk me through releasing a new version to the App Store and Google Play.

   What a good answer covers

   • Covers code signing, build numbers and release notes.
   • Uses TestFlight and Play testing tracks for beta users.
   • Knows store review can reject an app, and plans time for it.
   • Uses staged rollout on Google Play and phased release on iOS.
   • Has a plan to pause or patch if crashes appear.

5. In Swift, what is a retain cycle and how do you avoid one?

   What a good answer covers

   • Explains that two objects hold strong references to each other, so memory is never freed.
   • Mentions automatic reference counting.
   • Uses weak or unowned references and capture lists in closures.
   • Finds leaks with Xcode Instruments or the memory graph.

6. How do Kotlin coroutines differ from threads, and how do you use them in an Android screen?

   What a good answer covers

   • Describes coroutines as lightweight and suspendable.
   • Ties scope to the ViewModel or lifecycle so work is cancelled when the screen goes away.
   • Picks the right dispatcher for network, disk and UI work.
   • Handles errors and cancellation clearly.

7. How would you secure data in Firebase or Supabase for an app where each user sees only their own records?

   What a good answer covers

   • Uses Firebase security rules or Supabase row-level security, not checks in the app alone.
   • Ties each record to the signed-in user ID.
   • Keeps admin keys and service roles off the device.
   • Tests the rules with users who should be blocked.
   • Keeps personal data to what the app needs.

8. How do you use an AI coding tool such as Claude Code in your mobile work, and how do you check what it produces?

   What a good answer covers

   • Uses it for boilerplate, tests, refactors and explaining unfamiliar code.
   • Reads every change and runs the app on a device.
   • Writes or runs tests before accepting code.
   • Keeps secrets and customer data out of prompts.
   • Knows when the tool gets platform details wrong, such as outdated APIs.

1. A release goes live and crash reports spike on one Android model. What do you do first?

   What a good answer covers

   • Pauses the staged rollout.
   • Reads crash logs to find the cause and the affected OS version or device.
   • Reproduces the issue on the same device or an emulator.
   • Ships a hotfix or a remote switch that disables the feature.
   • Tells the product owner and writes down what to change in testing.

2. Apple rejects your update because of a review guideline you did not expect. How do you respond?

   What a good answer covers

   • Reads the rejection message and finds the exact guideline.
   • Replies in the review thread with clear information or a demo account if needed.
   • Fixes the issue if it is valid, and resubmits quickly.
   • Tells the team about the delay and checks the rest of the release plan.
   • Adds a pre-submission checklist for the future.

3. A list screen scrolls with visible lag on older, low-cost Android phones. How do you find and fix it?

   What a good answer covers

   • Profiles with Android Studio tools before changing code.
   • Checks image sizes, caching and work done on the main thread.
   • Uses lazy lists and pagination.
   • Tests again on a real older device.
   • Sets a simple target, such as no dropped frames while scrolling.

1. Tell me about a time a designer wanted something that clashed with iOS or Android conventions. What happened?

   What a good answer covers

   • Explains the user impact, beyond personal preference.
   • Shows the designer how the platform behaves, with examples or a quick prototype.
   • Finds a compromise that keeps the brand look.
   • Describes the result.

2. Describe a release where you had to cut scope to hit a deadline.

   What a good answer covers

   • Describes how you chose what to cut with the product owner.
   • Protects core flows and anything affecting security or data.
   • Communicates the trade-off early.
   • Records what was left out and schedules it.

1. Your app collects phone numbers and NRIC numbers at sign-up for a Singapore service. What concerns do you raise under the Personal Data Protection Act (PDPA)?

   What a good answer covers

   • Asks whether each item is needed, since NRIC collection is restricted to specific cases.
   • Gets consent and states the purpose clearly in the app.
   • Protects stored and transmitted data.
   • Plans for access, correction and deletion requests.
   • Suggests the organisation's data protection officer reviews the design.

2. You join a team building a mobile app for a financial institution regulated by the Monetary Authority of Singapore (MAS). What security points do you raise?

   What a good answer covers

   • Keeps data encrypted on the device and in transit.
   • Considers jailbreak and root detection, and certificate pinning.
   • Asks for strong sign-in and transaction checks.
   • Avoids logging personal or account data.
   • Follows the institution's technology risk and audit rules, and checks third-party libraries.

Common questions about a mobile app developer job

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