Why pre-screen mobile developers before the technical interview
Mobile is unforgiving in a way web is not. A bad release sits on people's phones until they update, the store review process gives you no quick fix, and a crash on a device you have never held is still your crash. Developers worth hiring watch their crash rate and know which devices cause it. A short screen asks for that number and what caused the worst spike.
What actually matters when screening Mobile Developer candidates
- 01
Technical proficiency
Probe depth in Swift/SwiftUI or Kotlin/Jetpack Compose: lifecycle handling, concurrency (coroutines, async/await), dependency injection, and how they manage memory leaks or retain cycles.
- 02
Systems and trade-offs
Ask how they structured offline sync, caching, and API layers; probe choices between native, React Native or Flutter, and how they kept app size and cold start low.
- 03
Evidence and rigour
Check how they measure quality: crash-free session rate in Crashlytics or Sentry, XCTest or Espresso coverage, staged rollouts, and diagnosing device-specific bugs from logs.
- 04
Collaboration and communication
Test how they work with designers on pixel and motion specs, handle App Store or Play Store review rejections, and coordinate releases with backend and QA.
Pre-screening questions to ask Mobile Developer candidates
12 questions grouped by what they test. Ask the same set in every screen and score answers on a consistent scale, or send them as an async video screen and compare answers side by side.
Apps in the stores
3 questions01Have you had an app published in a mobile app store, and can you share links?
Listen forLive listings with their own contribution described, and an account of whether they still maintain it.
Nothing published, or apps listed where their involvement cannot be described concretely.
02Can you share examples of apps where you made significant contributions?
Listen forSpecific features they built end to end, with the hard part of each described honestly.
Contribution described at team level, or features claimed with no technical detail.
03Can you explain a time when you had to build under a tight deadline?
Listen forScope cut deliberately with quality protected on stability, and technical debt recorded rather than hidden.
Testing skipped to make a date, or shortcuts taken that were never revisited afterwards.
Real device range
3 questions04Which mobile platforms have you developed for?
Listen forGenuine depth on at least one platform, with the platform conventions and review process understood.
Both platforms claimed with shallow experience on each, or store review rules not known.
05How familiar are you with the main mobile programming languages?
Listen forLanguage depth including memory and concurrency behaviour on the platform they work in.
Language use limited to following framework patterns, or no awareness of memory management.
06Do you have experience with cross-platform development frameworks?
Listen forA clear view of the trade-offs, with a case where native code was still required for a feature.
Cross-platform presented as free, or no awareness of where it breaks down in practice.
Crashes diagnosed
3 questions07What steps would you take to diagnose and fix an app crashing on some devices?
Listen forCrash reporting used to isolate device, version and path, with the cause reproduced before fixing.
Fixes applied on guesswork, or crash reports not monitored after a release.
08How do you ensure performance and responsiveness in a mobile app?
Listen forProfiling on real hardware, with startup time, main thread work and memory pressure all measured.
Performance judged on a high-end device, or no measurement before and after optimisation.
09Can you share your process for troubleshooting a problematic application?
Listen forA structured approach using logs, reproduction steps and device conditions rather than trial and error.
Problems resolved by changing things until they stop, or no reproduction before a fix.
Releases handled
3 questions10How do you handle older app versions still running on user devices?
Listen forBackward compatibility planned for, with server interfaces versioned and forced upgrades used sparingly.
Server changes shipped assuming everyone updates, or no plan for users on old versions.
11What is your approach to securing data in mobile applications?
Listen forSecrets kept off the device, sensitive data stored in platform secure storage, and transport pinned where warranted.
Keys embedded in the app binary, or sensitive data stored in plain preferences files.
12Do you have experience with source control and release processes?
Listen forBranching and review as normal practice, with staged rollouts used to limit the damage of a bad build.
Releases pushed to all users at once, or no ability to halt a rollout when crashes appear.
How to score responses
Score every candidate on the same four criteria immediately after the screen. At this stage you are shortlisting for panel interviews, not making the final call.
Technical proficiency
35%5Names specific APIs and language features, explains threading and lifecycle edge cases, and cites code they wrote to fix them.
Systems and trade-offs
25%5Defends architecture decisions (MVVM, modularisation, local persistence) against alternatives, with concrete cost in build time, size, or battery.
Evidence and rigour
25%5Quotes real crash-free percentages, ANR rates, or frame timings before and after, and describes the instrumentation that proved the fix.
Collaboration and communication
15%5Describes negotiating scope with design and product, and owning a store submission through rejection, resolution, and phased release.
A bad release sits on people's phones until they update. A one-way video screen asks what their crash rate was.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for this role take?
Fifteen minutes across eight to ten questions, answered async, with store links. Enough to establish what shipped, test their debugging approach, and check release and security practice.
Should I ask for published apps?
Yes, with a note on what part was theirs. A store listing proves something shipped; the useful detail is which features they built and whether they still support it.
Evaluating answers
What is the strongest signal when screening this role?
A crash rate they can quote and the cause of the worst spike. Developers who own an app in production track it. Anyone who has not looked has not carried a release.
How do I judge their device awareness?
Ask how they handle older devices and versions. Real answers cover a minimum supported version chosen from actual usage. Anyone testing only on current flagship hardware will ship crashes.
Go deeper on this role
Sanat has been hiring since 2012 and watching the recruitment industry change up close ever since, and turned that screening process into Hirevire's video screening platform. LinkedIn
