Web App Development
Web App Development for Startups That Ship Fast
We build production-ready web apps for startups in 3–7 days. AI-assisted development reviewed by senior engineers — so you launch with confidence, not technical debt.
Why Startups Choose Greta for Web App Development
You are burning runway while your dev team debates architecture. Most startup founders we talk to have spent 6+ months and $50,000 on a product that still is not live. That is not a tech problem — it is a process problem. At Greta Agency, we ship startup web apps in 3–7 days using AI-assisted development reviewed by senior engineers. Our system eliminates the estimation theater, the sprint planning overhead, and the endless 'almost done' status updates that drain startup momentum.
The startup web app development market is flooded with agencies quoting 6-month timelines and $150,000 budgets for what is, functionally, a CRUD app with authentication. We disagree with that model entirely. Your first version does not need to be perfect — it needs to be in front of users. We build the version that gets you there fast, with a codebase clean enough that your future CTO will not curse our names when they inherit it.
Non-technical founders face a sharp challenge: you cannot evaluate what you cannot build. We give every startup client access to a readable, documented codebase from day one, with no black boxes and no vendor lock-in. You get the full Git repository at handoff. Your future developers can extend it, a different agency can maintain it, or you can hire in-house engineers to take it forward — because the code is yours, completely and unconditionally.
Our Approach to Web app development for startups
Every project follows our 4-step vibe-coding process — AI handles the boilerplate, senior engineers handle the craft. From idea to live product in 3–7 days for MVPs.
Discovery
We spend 4–8 hours understanding your core user journey, not your entire feature wishlist. The key question we ask every founder: what is the single action that creates value for a user? That answer becomes the MVP scope. Everything else is documented as phase two. This constraint is uncomfortable but it is the reason our clients launch in days instead of quarters.
Design
Using Figma and your brand guidelines, we wireframe every core flow in 1–2 days. You see exactly what we are building before a single line of code is written. We share the prototype link, collect feedback in one consolidated round, and finalize scope. No surprise UI decisions, no 'we assumed you meant' moments mid-build.
Build
Our AI-assisted stack — Next.js 15, Supabase, TypeScript — cuts 60–70% of boilerplate time. AI generates the scaffolding: auth flows, database migrations, API routes. Our senior engineers write the business logic, review every PR, and make every architectural decision. You get production-grade code at prototype speed without the shortcuts that create technical debt.
Launch
We configure your domain, SSL certificate, error monitoring via Sentry, and basic analytics via PostHog. You get a pre-launch checklist of every feature validated against your acceptance criteria. We flip the switch to production together and stay online for the first 72 hours to catch anything the testing environment missed.
What You Get
Every web app development for startups engagement includes these deliverables — scoped before we start, delivered before we invoice.
- Full Next.js 15 web application with App Router and TypeScript configured in strict mode
- Supabase database with schema migrations, indexes, and Row Level Security policies
- Authentication system: email/password, Google OAuth, and magic link sign-in
- User dashboard with role-based access control and protected API routes
- Stripe integration configured for one-time payments or recurring subscriptions
- Responsive, mobile-first UI built with Tailwind CSS component library
- Vercel deployment with staging and production environments, preview URL per PR
- Error monitoring (Sentry) and product analytics (PostHog) fully configured
- Admin panel for user management, content editing, and basic data operations
- Complete handoff: Git repository, architecture docs, Loom walkthrough, and one training session
Tech Stack We Use
We build startup web apps on a stack that is both fast to ship and designed to scale: Next.js 15 with App Router for server-rendered pages that load in milliseconds, React 19 for interactive components, TypeScript throughout for a codebase your future CTO will not hate, Supabase for authentication, real-time subscriptions, and a managed PostgreSQL database, Stripe for revenue from day one, and Vercel for zero-config deployments with automatic preview environments. This is not a stack we invented for your project — it is the same stack we have used across 30+ startup builds. We know its failure modes, its scaling limits, and every sharp edge. That experience is worth more than a bespoke stack assembled fresh for each client.
Case Study
SEO Pilot — From Zero to 500 Users in 30 Days
SEO Pilot is a keyword-research SaaS built for a solo founder who had been bootstrapping for 8 months without a working product. In 4 days, our team shipped a fully functional web app with user authentication, a multi-step keyword analysis flow, and a Stripe subscription paywall. The founder launched with a single Twitter thread and had 47 signups within hours. Within 30 days, SEO Pilot had 500+ active users and a 12% paid conversion rate. The founder raised a pre-seed round 60 days after launch, citing the working product as the decisive factor in investor conversations.
Read full case studyPricing Transparency
Startup web app development at Greta starts at $5,000 for a scoped MVP — authentication, core user flow, one Stripe integration, and Vercel deployment. Full-featured builds with admin panels, multi-role access, and third-party integrations run $15,000–$35,000. All projects include full code ownership, two revision rounds, deployment configuration, and one week of post-launch support. No equity, no retainers unless you want them, no surprise invoices.
MVP
From $5,000
3–7 business days
Full Build
From $15,000
2–4 weeks
All projects include full code ownership, two revision rounds, Vercel deployment, and one week of post-launch support. No hidden fees.
Frequently Asked Questions
How long does it take to build a startup web app?
Most MVP-scoped startup web apps are live within 3–7 business days. Full builds with admin dashboards, complex user flows, and third-party integrations typically take 2–4 weeks. We do not pad timelines. When we commit to 5 days, we mean 5 days — and we have shipped dozens of projects on that schedule.
Do you take equity instead of cash?
No. We work for flat-rate cash only. Equity deals misalign incentives and slow projects down. Our published pricing means you know exactly what you are paying before we start, with no ambiguity about what is in scope.
What if I am non-technical and cannot review code?
That describes most of our clients. We document every architectural decision, record Loom walkthroughs of the finished product, and write a plain-English summary of what was built and why. You will never need to read TypeScript to understand your own product.
Can you work with my existing codebase?
Yes, but we assess first. We need 2–3 hours to audit your existing code before committing to a timeline. Some codebases are clean extensions of our stack — others need a full rewrite to build efficiently. We tell you honestly which situation you are in.
Do I own the code after the project ends?
100%. You receive the full Git repository with complete commit history, no licensing restrictions, and no lock-in to Greta tooling. Deploy it anywhere, hire a different team to extend it, take it completely in-house — it is yours unconditionally.
What is the minimum budget to work with Greta?
The floor is $5,000 for a scoped MVP. If your budget is below that, we recommend validating with a no-code tool first (Bubble, Webflow) and returning when you have evidence of demand. Building custom software before you know users want it is the most expensive MVP mistake we see.
Will the product be investor-ready?
Yes. We build to production standards, not demo standards. Every app ships on a real domain with real auth, real payments, and real error handling. We have had clients close pre-seed rounds using exactly the product we shipped — no polish sprint needed.
How do you handle post-launch bugs?
Every project includes one week of post-launch support at no extra cost. Critical bugs discovered in that window are fixed free. After that, we offer retainer plans or fixed-price bug-fix engagements. We do not disappear after delivery.
Ready to ship?
Ready to build your startup's web app?
Start Your ProjectOr reach us directly at hello@greta.agency
Written by the Greta Agency team · Last updated April 2025