Startup app development that closes funding rounds .

You need an app that proves product-market fit and passes investor scrutiny. We build apps that help startups raise $27M+ and scale to millions of users.

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$27M+ Raised
10K→200K Users
8-12 Week MVPs

Why most startup apps fail funding rounds.

You built an MVP with contractors. It works—barely. Now you're raising and VCs want to see your code.

What they find:

  • • No automated tests (fails technical review)
  • • Security vulnerabilities (kills enterprise deals)
  • • Can't scale past 10K users (blocks growth)
  • • Takes 3 weeks to ship simple features (too slow)
  • • No documentation (looks like mess)

What happens next:

Your term sheet gets pulled. You spend 6 months rebuilding. You burn $200K+ fixing problems you shouldn't have had.

Every week you delay costs $50-100K in runway.

Get Your Free Technical Audit

We'll tell you exactly what's broken and how to fix it.

What funded startups actually need.

Pre-seed to Series A startups don't need perfect code. They need apps that move fast and pass investor scrutiny.

Pre-seed (idea to MVP)

  • • Prove your hypothesis in 8-12 weeks
  • • Ship to app stores with real users
  • • Learn what actually matters
  • • Raise your first $500K-$2M

Seed ($500K-$5M raised)

  • • Prove product-market fit with 5K-50K users
  • • Ship features weekly, not monthly
  • • Handle growth without constant firefighting
  • • Prepare for Series A due diligence

Series A ($5M-$15M raised)

  • • Pass technical due diligence first time
  • • Scale from 50K to 500K+ users
  • • Build features that differentiate
  • • Attract senior engineering talent

We've built apps at every stage. We know exactly what you need when.

Get Stage-Appropriate Roadmap

We'll tell you exactly what you need for your stage.

How we build startup apps differently.

Traditional Agency Vermillion
Build what you ask for without questions Tell you what you actually need
Bill hourly forever with no end date Fixed scope and timeline you can budget
Use junior developers to keep costs low Only senior engineers (10+ years)
Disappear after launch Train your team and walk away
Optimize for their profit Optimize for your next funding round

"Most agencies said yes to everything. Vermillion told us no to 60% of our ideas and explained why. They saved us 4 months."

— Seed founder

Pre-seed: MVP development in 8-12 weeks.

You have an idea and $100K-$500K to prove it. You need an MVP fast.

What we build:

One core feature done extremely well. Not ten features done poorly. We help you pick the right one.

Included in every MVP:

  • ✓ User authentication
  • ✓ Your core feature
  • ✓ Basic profiles and settings
  • ✓ Push notifications
  • ✓ Analytics
  • ✓ Admin dashboard
  • ✓ iOS and Android apps
  • ✓ Backend API
  • ✓ Database
  • ✓ Hosting

Not included (add after validation):

  • ✗ Social features and UGC
  • ✗ Payment processing
  • ✗ Complex onboarding
  • ✗ Multiple user roles
  • ✗ AI features

Tech stack for speed:

  • • React Native + Expo (ship both platforms)
  • • TypeScript (catch bugs early)
  • • Zustand (simple state)
  • • Zod (runtime validation)
  • • Expo Updates (instant fixes)
  • • NestJS or Python backend
  • • PostgreSQL database

Timeline:

  • • Week 1-2: Wireframes, flows, planning
  • • Week 3-8: Core development
  • • Week 9-10: Testing on 20+ devices
  • • Week 11-12: App store launch

Investment: $80K-$150K depending on complexity

Submit to YC or Techstars. Raise your first $500K-$2M. Prove product-market fit.

Start Your MVP

Seed: Product-market fit in 12-16 weeks.

You raised $2M-$5M. Your MVP has 5K users and they love it. Now you need to scale without breaking.

Common problems at this stage:

  • • App crashes at 10K users
  • • Every feature takes 3 weeks
  • • Your contractor left and nobody understands the code
  • • Performance is terrible on Android
  • • You can't hire engineers because the codebase is a mess

What we rebuild:

  • • Architecture that scales to 100K+ users
  • • Clean code senior engineers want
  • • Automated tests so you ship confidently
  • • Performance optimization
  • • Documentation investors read

Deliverables:

  • • Rebuilt app with clean architecture
  • • 80%+ test coverage
  • • Technical documentation
  • • Developer onboarding guide
  • • Deployment automation
  • • Monitoring and alerting
  • • Security audit and fixes

Timeline: 12-16 weeks | Investment: $300K-$400K

Hire senior engineers. Scale to 100K users. Prepare for Series A.

Rebuild Your App

Series A: Pass due diligence in 8-12 weeks.

You have 50K-200K users. You're raising $10M-$20M. VCs will audit your code.

What VCs check during technical due diligence:

  • • Architecture documentation (can this scale?)
  • • Test coverage (is this maintainable?)
  • • Security audit results (is this safe?)
  • • Performance under load (will this break?)
  • • Technical debt assessment (how much to fix?)
  • • Team capability (can they execute?)

What fails due diligence:

  • ✗ Test coverage under 50%
  • ✗ No documentation
  • ✗ Security vulnerabilities
  • ✗ Can't scale past current users
  • ✗ Business logic in UI code
  • ✗ No monitoring or alerting

How we prepare you:

  • ✓ Architecture docs with diagrams
  • ✓ 80%+ test coverage
  • ✓ Security audit and fixes
  • ✓ Load testing
  • ✓ Code quality improvements
  • ✓ Monitoring and alerting

Timeline: 8-12 weeks | Investment: $150K-$250K

Pass technical due diligence first time. Close your Series A.

Prepare for Series A

Clean architecture for startup apps.

Most startup apps have business logic mixed with UI code. This fails due diligence and blocks hiring.

The problem:

Your contractor put everything in React components. You can't test logic without running the app. Senior engineers look at your code and say no to your offer.

Business Logic Layer (Pure TypeScript)

  • • Domain models and entities
  • • Business rules and validation (Zod)
  • • Use cases and workflows
  • • Zero React dependencies
  • • 100% testable without UI

State Management Layer (Zustand)

  • • Application state stores
  • • API client interfaces
  • • Cache management
  • • Offline synchronization

Presentation Layer (React Native)

  • • UI components and screens
  • • Navigation and routing
  • • Form handling
  • • Platform-specific code

For due diligence: VCs see clean separation. Logic is testable. Architecture is documented.

For hiring: Senior engineers see clean code. They say yes to your offer.

For velocity: Logic is in one place. Tests are fast. Changes are safe.

React Native + Expo for startup speed.

We use React Native + Expo for 90% of startup apps. Here's why.

Speed to market:

  • • Build iOS and Android from one codebase
  • • Ship MVP in 8-12 weeks not 16-20
  • • Deploy fixes in 20 minutes not 48 hours
  • • Iterate daily with hot reloading

Cost efficiency:

  • • One team instead of two
  • • $150K for MVP instead of $300K
  • • Half the maintenance cost
  • • Easier hiring

Over-the-air updates (game changer):

Critical bug at 11pm Friday? Push fix via Expo Updates in 20 minutes. Users get it automatically. No app store submission.

When we don't use React Native:

  • • Video or audio processing apps
  • • Complex AR features
  • • Apple Watch primary experience
  • • Apps where every millisecond matters

For everything else? React Native + Expo wins.

PicklePlay: 10K users to 200K users in 12 weeks.

The Challenge

PicklePlay raised $2M Seed with 10K users. Their app was broken. 30% crash rate. 2.8★ rating. Poor architecture. Series A investors saw the metrics and walked.

What We Did

Complete rebuild in 12 weeks. Clean architecture with Zod validation. Zustand for state. Python backend. 82% test coverage. Sentry for errors. Expo Updates for instant fixes.

The Result

Crash rate:

30% → 0.8%

App rating:

2.8★ → 4.5★

Users:

10K → 200K

Exit:

Acquired by UTR

"Vermillion rebuilt our app in 12 weeks. We went from losing users daily to 200K active users. UTR acquired us shortly after."

— Blake Renaud, Founder, PicklePlay

Ready to scale like PicklePlay?

Get Your Success Roadmap

Investment breakdown for startups.

Pre-seed MVP

Investment: $80K-$150K | Timeline: 8-12 weeks

Working app on both stores. Raise $500K-$2M. Prove PMF.

Seed product rebuild

Investment: $300K-$400K | Timeline: 12-16 weeks

Scalable app, tested, documented. Scale to 100K users. Raise Series A.

Series A due diligence prep

Investment: $150K-$250K | Timeline: 8-12 weeks

Documentation, tests, security audit. Pass DD. Close $10M-$20M.

Most clients use unspent R&D tax credits for payment.

Is this for you?.

You're Ready If:

  • ✓ You're pre-seed to Series A
  • ✓ You need to move fast without breaking things
  • ✓ You want to pass technical due diligence
  • ✓ You have $80K+ budget or R&D credits
  • ✓ You can make decisions in under 1 week

You're Not Ready If:

  • ✗ You're post-Series B with strong eng team
  • ✗ You need the absolute cheapest option
  • ✗ You can't start in the next 60 days
  • ✗ You take 3+ weeks to make decisions
  • ✗ You want someone to just say yes

We work with 12 clients per year. Seven spots left for 2025.

Claim Your Spot

Limited availability. Book your strategy session now.

Frequently asked questions.

How long does it take to build a startup app?

MVP: 8-12 weeks. Full product: 12-16 weeks. Series A prep: 8-12 weeks.

How much does startup app development cost?

MVP: $80K-$150K. Seed rebuild: $300K-$400K. Series A prep: $150K-$250K.

Should I use React Native or build native?

React Native for 90% of startups. Native only if you have 2x budget and time.

Can you help me pass technical due diligence?

That's our specialty. We've helped clients pass DD and raise $27M+.

Do you work with non-technical founders?

Yes. We explain everything in plain English. You make the decisions.

What happens after you build my app?

We train your team and hand off. Or you hire us for maintenance ($8K-$25K/month).

What happens next.

Book a strategy session. We'll review your app, your goals, and your timeline. You'll get honest advice on what you actually need.

No pressure. No sales pitch. Just straight talk from engineers who've built apps for 200+ startups.

Book Strategy Session

Session covers:

  • • App audit (if you have one)
  • • Technical roadmap for your stage
  • • Timeline and milestone breakdown
  • • Investment estimate
  • • Team structure recommendations

If we work together, the $5,000 applies to your project.