SeoulTop App & Web Developers in Seoul
Software development for Seoul. We build high-performance mobile apps and web platforms for South Korea's gaming, fintech, and super-app ecosystems.
App369 is a founder-led software studio based in Miami, Florida. We build custom mobile apps, web platforms and AI features for businesses in Seoul and beyond, working remotely on Eastern Time.
- Fiverr
- 5.0 · 126 reviews
- Own product
- Workspace369
- Fixed-price offers from
- $450
Why App369
Why Seoul Businesses Choose App369
What Seoul teams should know before working with App369.
Serving Seoul, Pangyo Techno Valley, Incheon, and the Seoul Capital Area
Focus on gaming, fintech, and super-app platforms
Development for Korea's mobile-first, 5G-first culture
Understanding of Korean business practices including PIPA (Personal Information Protection Act) compliance and KRW payment integrations
What we build
Software Development Services in Seoul
From Pangyo Techno Valley to the Samsung/Kakao ecosystem in Gangnam, we deliver software built for Korea's ultra-connected, mobile-first market.
Mobile Apps
iOS and Android apps built with Flutter from one codebase, from concept to App Store launch.
- iOS & Android
- Cross-Platform
- App Store Optimization
- Maintenance & Updates
Web Development
Fast websites and web applications, built for search and for phones first.
- Custom Design
- E-Commerce
- SaaS Applications
- SEO Optimization
Custom Software
Internal tools, integrations and back-office systems engineered around how your team already works.
- Enterprise Development
- API Integration
- Cloud Migration
- Technical Consulting
How it works
Our 4-Phase Development Process
A written scope and four clear phases keep Seoul projects predictable.
Discovery
Understanding your vision, goals, and market requirements through stakeholder interviews and competitive analysis.
Design
Creating clear UI/UX with interactive prototypes you can click through before we build.
Development
Building with Flutter, Vue.js, Node.js, and GCP using 2-week Agile sprints with weekly milestone reviews.
Launch
Deployment to production with crash and uptime monitoring and ongoing maintenance.
Technologies
- Flutter
- TypeScript
- Node.js
- GCP
- Firebase
- Vue
- JavaScript
- Python
Questions
Frequently Asked Questions
How long does a typical project take?
It depends on scope. As a rough guide, a marketing website takes 4-8 weeks, a web application 2-4 months, and a mobile app 3-6 months. Every Seoul project starts with a written scope and milestone plan, so you know the timeline before any build work starts.
Do you provide ongoing support?
Yes. After launch we offer maintenance that covers bug fixes, iOS and Android OS updates, security patches, dependency upgrades and small feature work, so your Seoul app keeps working as the platforms change.
What's your pricing model?
App369 uses project-based pricing with a 50/50 payment structure: 50% upfront and 50% on completion. Current ranges are published on our fee structure page, and smaller fixed-price packages are available for well-defined work.
Can you work with existing projects?
Yes. We take over existing codebases, especially Flutter and Firebase apps, for code audits, bug fixes, new features and migrations. Seoul businesses with an app that stalled or a developer who left can start with an audit before committing to a larger build.
What technology do you use?
Mostly Flutter for iOS, Android and web apps from one codebase, Firebase and Google Cloud for backends, and Vue/Nuxt for websites. For AI features we integrate large language models for assistants, document extraction and automation.
Your Development Partner
Simon Dziak
As founder of App369, I personally oversee every project we take on, from scoping to launch. I build with Flutter, Firebase and Google Cloud, and I also built and run Workspace369, a client-management platform for freelancers and small businesses. Based in Miami, Florida, we serve clients across Seoul and nationwide.
Start Your Seoul Project
Fiverr reviews / 95 on app work
What buyers said about working with Simon
“It was a pleasure speaking with Szymon. This guy knows what he’s doing and I’m looking forward to working with him.”
A buyer in the United States, April 2022. Custom order on Fiverr “Simon has lived up to his bio and then some. This has been a large piece of work with unique, complex and new components for both of us and he has navigated the entire build with persistence, professionalism and ingenuity. He has delivered on what was agreed on the back and front end, kept in constant communication and focused on the deadline. I put in place a reasonably structured communication and delivery model, so I felt the deliverable & expectations were clear, and I was holding up my end of the bargain, and Simon then met these expectations and more by holding up his.”
A buyer in the United States, April 2022. App development on Fiverr “I highly recommend this developer. He helped me create an amazing application, that is definitely going to help my business generate a lot more income. He is fast, intelligent, and hard-working. Look no further, you found the perfect developer for your project.”
Mark, United States, March 2022. App development on Fiverr
Read the whole story
- Sixteen five-star reviews from one buyer: mobile apps, app design and a Shopify store (Mark, United States)
- A large custom app build, delivered on the back end and the front end (A buyer in the United States)