Dev, startup, AI experts
at 1/20 the cost
build your platform for you
23-year veteran James handles scoping, development,
deployment, and teaching — all in 4 hours.
Four hours, all the way to a deployed server — together.
A 23-year veteran developer builds with you on screen, in real time. If we can't show a result in 30 minutes, you get a full refund.
You needed months, tens of thousands of dollars, and a team of several developers.
One 23-year veteran builds the same scope with you in 4 hours, at 1/20 the cost.
23 years in Korea's startup industry. Through Insomnia agency, James has shipped over 350 platforms.
- Startups
- Getcha · HelloNature · FastCampus · LoadComplete · KCD · PeopleFund · SoccerBee + 200 more startups
- Enterprise
- KT · Cheil · POSCO · Lotte Department · Lotte Data
What you leave with
- You can build features and operate the service yourself.
- A scope that used to cost 10× — now in your hands within 4 hours.
- Optional follow-up sessions and a maintenance subscription to grow further.
See what 4 hours can change — in 5 minutes
How a 1:1 consulting session runs and what you walk away with, summarized in a short video.
23-year AI · Dev · Startup Expert
Full-stack AI and development expert — former startup CTO and agency founder
James (Sunghoon Lee)
23-Year Full-Stack AI · Dev Expert
₩2B annual revenue, ₩8.5B cumulative — hundreds of complex platforms shipped
Using AI agents to handle more work than a company of dozens of employees
3,000+ students trained in development, vibe coding, and entrepreneurship
Repeat judge for government startup programs and hackathons
heyjames YouTube
20K+ Subscribers
최근 추천 영상
Why you should work with James
Built hundreds of startup platforms — combining a developer's eye with a founder's perspective.
Ran an agency to 8.5B KRW in revenue. Sales, contracts, operations — all hands-on experience.
Through hundreds of projects, James has built deep domain knowledge across legal, tax, real estate, advertising, education, startups, monetization, programming, infrastructure, and AI.
James keeps shipping products
Not just teaching or consulting — James releases his own products using the same 4-hour session format. Every one is fully built including the admin panel and ready to operate, and you can also acquire any of these services for the same number of sessions shown.
Why non-developers can't get to launch
There's a repeating pattern to why people learn vibe coding but never actually launch. Breaking that pattern is the core of this 4-hour session.
Common failure pattern
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People keep adding features without setting any operating policies.
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Security and risk reviews are skipped entirely.
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Multiple features get built at once, conflicting with each other.
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Each feature moves on before being reviewed or covered by tests.
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Ideas get explained to the AI in whatever order they come to mind.
How we actually work
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We split the work into the right unit and build one step at a time.
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After each build, we review the code and write tests.
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Risky pieces get verified in a simple structure first, then merged into the main flow.
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Each new feature is layered on top of verified ones for safe growth.
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We analyze the plan and structure it technically so the AI understands it clearly.
30 minutes to a real result on screen
In the first 30 minutes, James plans with you, builds an initial version, and deploys it to a test server — all live on screen.
Plan and prioritize
We listen to your idea and decide together what to build first.
Build the first version
We demo Claude Code prompts and skills on screen, building a working first version.
Deploy to a test server
We deploy to a real domain right there and confirm it's working.
If you're still not satisfied after seeing this, the full 4-hour consulting fee is refunded.
Live demo and know-how, all at once
A rough idea is enough. James asks the right questions and demonstrates Claude Code prompts and skills on screen as we build together.
All the essentials in one session
Auth, profile edit, account deletion, terms, privacy policy, admin pages, email sending, analytics, stats, and SEO — all covered in one session.
By the end of the session
You'll be able to build features and operate the service yourself. A scope that used to cost 10× to outsource, delivered in 4 hours.
What's next
Additional sessions
When you want to expand into new features, you can add as many follow-up sessions as needed.
Maintenance subscription
Ongoing support to handle whatever comes up while you operate the service.
Why James builds on Ruby on Rails
While JS full-stacks like React, Next, Vercel, and Supabase evolve in fragments, Ruby on Rails has settled into the strongest single-person full-stack for shipping a SaaS end-to-end. The gap only widens in the AI era.
The stack AI builds fastest
- Same feature in roughly 1/5 the code
- More fits in the AI's context — fewer hallucinations and rework
- Faster and more accurate than React + Express + Prisma
Code volume to deliver the same feature
One Rails instead of 100 libraries
- Long AI calls and email run on Solid Queue
- Realtime chat and notifications via built-in WebSocket
- Subscription billing and recurring jobs on a built-in scheduler
- Frontend, DB, cache, and storage in one package
One server runs the whole SaaS
- One VPS in Seoul region runs DB, files, scheduler, and web
- Operate for around $10/month until traffic really grows
- No stacked bill for Vercel + Supabase + Upstash + Resend + S3
Operations setup
- • Everything inside one VPS
- • Vercel (hosting)
- • Supabase (DB · auth)
- • Upstash (queue · cache)
- • Resend (email)
- • S3 (storage)
Out of the npm supply-chain blast radius
- Fewer dependencies = smaller attack surface
- Auth · CSRF · SQL injection · sessions handled by the framework
- API keys stay server-side — never leak to the client
Average dependencies in production
Rails
~30 gems
React / Next
~1,500 npm
One person ships end-to-end
- Rails: 1 person owns product → ops
- JS full-stack: FE · BE · DevOps · DBA split
- The secret behind shipping in 4 hours
Roles required
Rails
👤 × 1
JS full-stack
👤 × 4
Same shape one year later
- Rails conventions: same for 20 years
- Code AI wrote a year ago still composes cleanly today
- Successor handoff takes a fraction of the time
How often core frontend tooling churns
MVC · ActiveRecord · ERB
Router · State · Bundler
Rails 로 만들어진 회사들
AI 시대에도 살아남은 풀스택 — 세계 최대 코드 호스팅부터 국내 대표 서비스까지, 같은 프레임워크 위에서 운영되고 있습니다.
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GitHub
세계 최대 코드 호스팅
Microsoft 75억 달러 인수 -
Shopify
글로벌 이커머스 플랫폼
시총 약 1,500억 달러 -
Airbnb
글로벌 숙박 공유
시총 약 850억 달러 -
Stripe
온라인 결제 인프라
기업가치 약 700억 달러 -
Twitch
라이브 스트리밍
Amazon 9.7억 달러 인수
-
당근마켓
지역 기반 중고거래
기업가치 약 3조 원 -
마이리얼트립
여행 예약 플랫폼
누적 거래액 1조 원+ -
리멤버
비즈니스 네트워크
드라마앤컴퍼니 · 가입 400만+ -
업비트
암호화폐 거래소
두나무 · 국내 1위 거래소 -
잡플래닛
기업 리뷰 · 채용
기업 리뷰 600만+ 건
Can you build apps too?
Yes — as hybrid apps.
We build the mobile web first, then package it as an app. The single build runs across desktop browsers, mobile browsers, iPhone apps, and Android apps with the same UX and feature set. No need to build for four environments separately.
토스와 당근마켓을 비롯한 수많은 국내외 대표 서비스가 이미 하이브리드 앱 방식으로 제작되어 운영되고 있습니다.
Desktop Web
Mobile Web
iPhone App
Android App
Native features still work
Push notifications, in-app purchases (App Store / Play Store), camera and contacts access — anything that only works inside a mobile app is implemented alongside.
Packaging tech
We pick from Hotwire Native, Flutter, or React Native — whichever fits the service best.
Build it, together.
Four hours with a 23-year veteran. Full refund if we can't show a result in 30 minutes.
Prefer to learn solo? The courses are right here too.