Most of the bad mobile app builds we've seen come from the same root cause: the founder picked a vendor without a way to compare them, signed a fixed-price contract with vague deliverables, and discovered six months later that the team building their app didn't include a real iOS or Android engineer. The app shipped, kind of. The App Store rejected it twice. The Android version had a 3.7 crash rate per session. The agency moved on.
This article is the diligence process that prevents that outcome. It assumes you've already decided to build (if you're not sure, see native vs cross-platform and mobile app cost breakdown first).
The 9 questions to ask every shortlisted agency
1. Show me 3 apps you built that are live in the stores today
"Live in the stores today" is the active filter. Many agencies have impressive demo videos for apps that quietly never shipped or got pulled. Open the App Store, search for the agency's apps, read the reviews. A 3.5+ rating with 100+ reviews is a real signal of shipping competence. A demo reel is not.
2. Who handles native iOS issues? Who handles native Android issues?
Even on a "cross-platform" build using React Native or Flutter, you'll hit native issues, push notifications, in-app purchases, biometric auth, deep linking, App Store provisioning. A capable agency has at least one engineer with strong native iOS experience and one with strong native Android experience. Many cheaper agencies have neither and outsource these problems back to you.
3. What's your store-submission track record?
Specifically: how many apps have they submitted to App Store and Play Store, what's the rejection rate, and how do they handle rejection. The honest agencies will admit they've had 1 to 3 rejections per submission cycle and walk you through how they fix and resubmit. The dishonest answer is "we never get rejected."
4. How do you handle versioning and over-the-air updates?
You want to hear: phased rollouts (5% → 25% → 100%), separate dev/staging/prod builds via TestFlight and Internal Testing tracks, OTA updates via Expo Updates or CodePush for cross-platform JavaScript bundles, force-update logic for critical security fixes. If they look puzzled at this question, they haven't operated production apps.
5. What does your performance budget look like?
A 2026 mobile app should target: cold start under 2.5s, time-to-interactive under 4s, app size under 60 MB at install, frame rate at 60fps minimum on devices 3+ years old. Ask the agency to share an instrumentation plan: how do they measure these in production? If "we'll check it before launch," they don't have one.
6. Walk me through your release pipeline
Healthy answer: code → CI runs unit + UI tests → automated build via Fastlane → uploads to TestFlight + Play Internal Testing → QA + stakeholder smoke test → promotion to production. Time from PR merged to in-store: ideally under 24 hours for non-blocking changes. Manual store uploads from someone's laptop: red flag.
7. What does post-launch month 2 look like for us?
Apps that just shipped need a lot of attention. iOS and Android each release new OS versions every September/October and the resulting compatibility issues hit fast. Push permission rates dropping, Apple changing privacy rules, Google deprecating an API your app depended on. The agency's answer should be a clear retainer model with monthly hours allocated for these realities, not "we'll figure it out as it comes."
8. How do you handle App Store Optimization?
Most app dev agencies don't do ASO and that's fine, but they should know what it is and either offer it as a service or recommend a partner. We covered the basics in our ASO beginner's guide. If they say "ASO doesn't really matter," that's a sign they don't think about distribution.
9. What's the most painful production incident you've handled?
Real shipping experience produces battle stories. The agency that says "nothing has ever gone wrong" has either never shipped or never owned the post-launch phase. You want to hear specifics: a memory leak caught in production, a Sign in with Apple migration that broke 3 days after iOS upgrade, a backend rate-limit issue surfaced by a viral spike. Specifics signal experience.
Cost ranges for 2026
| App tier | Realistic quote (USD) | Timeline |
|---|---|---|
| Cross-platform MVP (1 platform feel) | $25k, $60k | 10, 14 weeks |
| Polished cross-platform v1 | $80k, $180k | 4, 6 months |
| Native iOS + Android v1 | $150k, $400k+ | 5, 9 months |
| Hardware-paired or AR/VR | $300k, $1M+ | 9, 18 months |
Quotes 40%+ below these benchmarks usually mean (a) you'll get a single platform built and the other "ported" badly, (b) the QA budget is zero, or (c) you'll inherit weeks of unpaid debugging. Quotes 50%+ above are usually pricing in consulting and project management overhead, not better engineering.
Contract clauses that protect you
Insist on these explicit clauses before signing:
- Source code in your Git org from day one. Read access from week 1, write access at handoff.
- Apple Developer + Google Play accounts in your name. Never the agency's. Migrating off them later is painful and sometimes impossible.
- Build artifacts (signing keys, certs, provisioning profiles) escrowed with you at every release. If the agency disappears, you can still ship.
- App Store Connect and Play Console admin access for you. Always.
- Third-party SDKs listed in writing. So you know what telemetry the app ships with.
- Scope-change protocol. Changes over $X get re-quoted before work starts.
The two-week pilot
If a build is over $80k, consider a paid 2-week pilot before signing the full contract. Scope: a clickable prototype, a working auth flow, one real backend integration, deployed to TestFlight. Cost: $8k to $15k. The pilot reveals more about the agency than three months of sales calls. The good ones will offer this; the bad ones will resist.
What to avoid entirely
- Agencies whose iOS apps don't have a native macOS equivalent if they claim native iOS expertise. Apple cross-pollination is a soft proxy for Apple-platform fluency.
- Anyone quoting "fixed-price for whatever you need." Real fixed-price requires real scope; what they're really offering is hourly with a price floor.
- Agencies that show you only HTML/CSS prototypes for an "app" pitch. If there's no real-device demo, the app probably doesn't exist yet.
Get a written response
Before signing, get the agency to write a 2-page response to your spec covering: their proposed architecture, the team they'd put on it, the timeline week-by-week, the scope explicitly in and out, and the post-launch retainer. Compare these documents side by side. The differences will be more revealing than any sales pitch.
If you want to put DevEntia on that comparison, we'll send you a written 2-pager within 48 hours. Tell us about your app here.