Sangyoon Lee
From: South Korea
Location: Seoul, KR
On Useme since 21 September 2026
About me
Full-stack engineer, 12+ years (web, mobile, backend). I take a product from first commit to production and keep it running.
- Replaced a live app's whole backend (serverless to Spring Boot) with zero forced app updates, as the only engineer. - Built 3 new services in 2 months alone, every deadline met. - Owned a Flutter app end to end for 2 years: backend, subscription billing, sign-in, release. - 10 years of real-time systems; 4 kinds of payment integration in production. - Recent: open-source MCP server for Google Search Console, WooCommerce plugin, IDE extensions.
Stack: Node/TypeScript, Python, PHP/Laravel, Java/Spring Boot, React, Flutter, PostgreSQL, Redis, Docker, AWS.
In writing, so every request and scope change stays on record; replies within 24h, weekends included (GMT+9). Before code you get a one-page spec with an acceptance checklist. Seoul-based, real name, ID-verified; my work is public on JetBrains, VS Code, WordPress.org and Atlassian. Paid only via Useme milestones.
Categories
CV / Résumé
Jul 2024 - Jul 2026
Lead Engineer
Wego Company
Built a kids news app (Flutter, iOS and Android) for a newspaper subsidiary. Rebuilt the backend on Spring Boot WebFlux with a GraphQL API, integrated one-off and recurring subscription payments, Google and Apple sign-in, and realtime features over G
Portfolio
Daily cron pulls a government open API, cleans the records and generates about 350 statistics pages on Cloudflare Workers and D1. Built solo, from the scraper and the schema to the pages and the deployment.
Spreadsheet reporting automation
Order and sales sheets that update themselves: raw rows in, cleaned data and a summary dashboard out, with formulas and scripts instead of manual copying. Delivered to paying customers on a Korean freelance marketplace.
My own SaaS, live. Connects Google Search Console to Claude and ChatGPT over MCP, mails a weekly report with 3 things to fix, and alerts on click drops. Built and operated solo: Cloudflare Workers, D1, OAuth, billing.
Extension published on the Visual Studio Marketplace. Re-runs .http request files and compares the responses, a lightweight API regression test inside the editor. Passed marketplace review.
Plugin listed on WordPress.org. Keeps Printful print-on-demand products in step with WooCommerce without deleting anything silently and without touching the customer cart. PHP, WooCommerce hooks, Printful API.
Jira dashboard gadgets (Atlassian Marketplace)
Gadgets published on the Atlassian Marketplace: goal gauge, countdown and filtered issue list. Atlassian Forge, React, Forge storage. Passed Atlassian security review and is live for public install.
Excel merge and cleanup macro
Merges many Excel files into one table, normalises columns and dates, removes duplicates and produces the summary sheet. Work that took a morning by hand now runs in one click. Sold as a product with real buyers.
Live service that finds and blocks invalid clicks on Korean search ads automatically. Detects repeated clicks from the same visitor, builds the block list and applies it. Built and run by me end to end: backend, scheduler, dashboard, Cloudflare deplo
Paid plugin on the JetBrains Marketplace (one of 7 I published). Renders Markdown in a real browser engine, follows the IDE theme, supports Mermaid diagrams. Java, IntelliJ Platform SDK. Passed JetBrains review.
Returns Google Trends interest over time, by region and related queries. Handles the 429 rate limit with cookie warm-up and proxy rotation so runs finish instead of hanging until the platform timeout.