Available for New Projects

Full-Stack Software
Development Partner

Silicon Valley-trained engineering team building production-ready mobile apps, web applications, and AI-powered products — fast and at scale.

4+ Apps in Production

Patent-backed Technology

iOS & Android Shipped

Start a Project View Portfolio

What We Do

Services

End-to-end software development, from product strategy to App Store launch.

Mobile App Development

Production-ready iOS & Android apps built with React Native. We've shipped 4+ apps to both stores — from MVP to scale.

React NativeiOSAndroidFirebase

Web Application Development

Full-stack web apps with Next.js, React, and modern backend services. Clean architecture, fast delivery.

Next.jsReactTypeScriptTailwind CSS

AI Integration & Automation

Integrate LLMs into your product, build AI pipelines, and automate workflows. We hold a patent on AI-based behavioral security.

OpenAIClaude APIAutomationAI/ML

MVP Rapid Prototyping

From idea to live product in weeks. We've validated multiple products in real markets — not just demos.

MVPMarket ValidationLaunchFirebase

Our Work

Portfolio

Real products, live in production — not demos.

Bloom Again (다시, 봄)

AI · Social · Senior

AI-powered safety-first social community for users 50+. Features patent-backed cognitive fingerprint technology for real-time scam and phishing detection.

React NativeFirebaseAI/MLiOS & Android

My Restroom (나의 화장실)

Location · Crowdsourced

Location-based restroom information platform with Naver Maps integration, user reviews, crowdsourced verification, and a report/reward system.

React NativeFirebaseNaver Maps APIiOS & Android

SOWANT (쏘원)

Social · Commerce

Preference-sharing platform for curators with good taste. Co-founded and serving as CTO — led app architecture and launch.

React NativeNode.jsFirebaseiOS & Android

Chambang (참방)

Local Business · Loyalty

Easy, fast customer loyalty app for small business owners. Contributed as a builder — handled product design and full-stack development.

React NativeFirebaseiOS & Android

Tech Stack

React NativeNext.jsTypeScriptFirebaseSupabaseTailwind CSSOpenAI APIClaude APINaver Maps APINode.jsFigmaVercel

Han Gyeol Ryu

CEO & Founder

ceo@effeffcorp.com

About the Founder

Silicon Valley engineer.
Startup builder. Product obsessive.

With an engineering career rooted in Silicon Valley, I've experienced firsthand how technology is the most powerful lever for solving real business problems. Development, to me, is not just about shipping features — it's strategic engineering design that translates business logic into measurable outcomes.

I favor data-driven agile execution over vague hypotheses. I rapidly prototype ideas, target real pain points, and refine with actual market feedback. As CEO of EFFEFF, I'm simultaneously building validated products across AI security, location services, and commerce.

Apps Shipped

Patent Pending

iOS & Android

Both Platforms

Get in Touch

Let's build something together.

Available for mobile app, web app, and AI integration projects. We usually respond within 24 hours.