The 7 Questions to Ask Any Mobile Dev Agency (And How SEM Nexus Answers Them)

First calls with mobile-dev agencies sound identical. Everyone claims senior engineers, end-to-end service, on-time delivery, real portfolios, AI-augmented tooling, and a passion for excellence. None of that surfaces the real differences. Seven specific questions do — and how each agency answers them tells you whether they can actually ship your app in 4 months or whether you're paying for vendor coordination overhead.

This is the list of questions I'd ask if I were hiring a mobile-dev agency tomorrow. Each one has a SEM Nexus answer attached so you can see the bar.

1. "Who is the senior engineer who will own my project, and will they be in discovery?"

A senior engineer in discovery is the single highest-leverage signal you can get. If the agency assigns junior engineers to discovery and only puts seniors on the build, the discovery is sales work and the architecture will be re-litigated in week 4.

SEM Nexus answer: Yes. The senior engineer who will own the architecture sits in discovery from day one. The same person writes the technical recommendation, picks the stack, and ships the spine. There is no hand-off between the discovery senior and the build senior. They're the same person.

2. "What's the fixed quote, and what triggers a re-quote?"

A real fixed quote is one where the agency takes the risk of underestimation, not you. If the quote is "estimated $80k–$120k," that's not a fixed quote, that's a range with the high end as the real number.

SEM Nexus answer: Fixed quote against v1, written down at the end of discovery. We eat overruns caused by us. Re-quotes are triggered only by material scope additions from the founder — a new feature, a new platform, a new integration. Scope changes are repriced explicitly, you approve or reject, then the timeline updates. Silent re-quotes don't happen.

3. "What stack are you most likely to talk a founder out of?"

This question reveals stack-lock instantly. A cross-stack agency has opinions about when each stack is wrong. A stack-locked agency has only one stack to recommend.

SEM Nexus answer: Depends on the project. We talk founders out of Flutter when their team is React-native and they don't have Dart skills (My Home Delivery's founder team was React — we picked RN). We talk them out of React Native when the project's hard part is audio engineering or custom UI rendering (Cerebyte — we picked Flutter). We talk them out of native when the project doesn't need native-first features and the cost of two codebases isn't justified.

4. "Show me a written technical recommendation from a recent discovery."

Most agencies will not have this artifact ready, because most agencies don't produce one. The recommendation is the difference between paid discovery and free discovery.

SEM Nexus answer: Yes. We'll redact the client name and show a recent example. The recommendation is one page, names the stack, names the hard part by name, names the integrations and architectural risks, and ends with the build quote. If an agency can't show you this artifact, ask why.

If you'd like to see a real SEM Nexus technical recommendation applied to your project, book a two-week discovery and we'll deliver one against your scope.

5. "How do you handle the cross-functional question when the design conflicts with the engineering budget?"

This is the seam test. A multi-vendor build has to round-trip the question through multiple companies. A one-team build resolves it in the same standup.

SEM Nexus answer: Same hour. The engineer turns to the designer at the next desk. They sketch two alternatives in 15 minutes. The PM (often the same person who ran discovery) checks with the founder on Slack the same afternoon. Decision is in sprint planning the next day. If an agency answers this with "the PM coordinates," ask how many days that coordination typically takes.

6. "What's the typical post-launch retainer cost, and what's included?"

A real post-launch retainer keeps your build alive after the App Store launch. The first 90 days post-launch are where the product is most fragile — bugs surface, App Store visibility ramps, user feedback floods in. If the agency leaves at v1, you'll be hiring emergency contractors at month 5.

SEM Nexus answer: $5k–$15k/month depending on scope. Includes v1.x feature development, App Store Optimization, growth experiments, retention work, crash and bug triage. Most clients keep us on retainer for 6–12 months post-launch. By the time they bring the build in-house (if they do), we hand off with 3 months of overlap.

7. "Tell me about a project you turned down — and why."

This question separates agencies that say yes to everything from agencies with judgment. A team that takes every inbound is a team that will overcommit on yours.

SEM Nexus answer: We turn down projects regularly. Most common reasons: the founder hasn't validated demand yet (we recommend they spend $500 on smoke tests before committing $40k to a build); the project's hard part is genuinely outside our specialty (deep AR/VR work, hardware firmware integration); the founder doesn't have time to be the PM on their side (the agency can't ship without an engaged founder no matter how senior the build team is). We've recommended founders not build apps at all — we've said "build a mobile-optimized web flow instead" twice in the last two years, both times the founder thanked us.

What the answers tell you, in aggregate

Run these seven questions against three agencies. Score each on a 1–3 scale per question. The agency that scores 18+ out of 21 is your candidate. Most agencies score 10–14 — fine answers but not great, and the gaps surface in the build.

SEM Nexus scores 21/21 on its own questions because the questions are designed to surface what SEM Nexus does that most agencies don't. If the same agency wrote a list designed for their strengths, they'd score 21/21 on theirs too. That's not the point — the point is that the SEM Nexus questions are the ones that actually predict whether your build ships on time, because they target the structural causes of slip:

• Vendor coordination overhead (Q1, Q5)
• Honest pricing (Q2)
• Stack appropriateness (Q3, Q4)
• Post-launch survival (Q6)
• Judgment (Q7)

How to weight the answers

If you only have time for three questions, ask:

1. Q1 — senior engineer in discovery. This is the single best predictor of build quality.
2. Q2 — fixed quote with explicit re-quote triggers. This is the single best predictor of build-cost reliability.
3. Q7 — projects turned down. This is the single best predictor of agency judgment.

A team that gives strong answers to all three is materially better than the average mobile-dev agency in 2026. SEM Nexus is built to win on exactly these three. That's not an accident — those are the structural advantages we've optimized for.

If you're scoping a build right now and you'd like to run the questions against us live, a two-week discovery is the cleanest way to see the answers in practice. The discovery itself is the demonstration. By the end of week 2, you'll have a fixed quote, a real sprint plan, a stack recommendation with written reasoning, and a clear answer to every one of the seven questions above. Most agencies cannot deliver that artifact in two weeks. We do.