The studio behind the work
CompletApp is a full-stack product studio based in Budapest, building cross-platform apps, web apps, and custom websites, with real backends behind them and the API integrations that connect an app to the systems a business already runs.
11+
Years building
10+
Products shipped
70+
Apps published
3,000,000+
Combined downloads
24h
Reply time
Hi, I am János
I am János, based in Budapest, Hungary, and currently the solo force behind this studio. I build with full-code Flutter, and for the web with modern tools like React and Astro. AI from OpenAI and Claude goes in where it earns its place.
Most of what I build starts from a blank page: an app, a backend on Supabase or Firebase underneath it, and nothing else in the way. That is the right answer more often than people expect, and it is how most of my work ships. Other projects arrive the other way round. The company already runs on something, and the job is software for the people doing the work that fits around that system instead of replacing it. You will find both kinds in my portfolio. Part of my job is telling you which one you actually need.
I am not a developer in the traditional sense. I am more of a business-minded person who uses technology as a tool to help others bring their ideas to life. My strength lies in turning concepts into functional, user-friendly apps that make a real impact. I own several apps that are live in the stores today, and together they have reached millions of downloads.
My journey into app development started in a completely different field: I am originally a biologist. My passion for building apps began back in 2015, and it has only grown stronger over the years. Since I never formally studied programming, I started in the world of no-code and became highly skilled with FlutterFlow. It was a fast, effective way to build and validate real products, and as my clients grew, so did their needs.
Beyond app creation, I have invested significant time into understanding the app business, from marketing and growth strategies to UI and UX design. It is all part of my commitment to delivering high-quality products, whether they are my own or for a client.
My ultimate vision is to help millions of people improve their lives in some way. Whether through my own apps or by helping others turn their ideas into reality, I am dedicated to making a positive impact, and I am excited to keep growing and sharing this journey with you.
How I work
Business first
Technology is a tool. Every decision serves your users and your bottom line.
Ship fast, ship right
Rapid delivery without cutting corners on quality or performance.
Full ownership
On full payment, all rights to your product and its code are yours.
Honest and direct
Clear scope, fixed price, daily progress, and no jargon.
Built on a modern, AI-native stack
The tools we use to design, build, ship, and scale your product.
Flutter
Mobile
React
Web
Astro
Web
WordPress
Web
TypeScript
Tooling
Tailwind CSS
Tooling
Firebase
Backend
Supabase
Backend
OpenAI
AI
Claude
AI
Stripe
Payments
RevenueCat
Payments
Resend
Comms
OneSignal
Comms
Vercel
Tooling
Cloudflare
Tooling