Byung Hyeon Choi

Backend Developer
choi8608@gmail.com · Seoul, South Korea

Summary

  • Backend developer specializing in high-throughput API platforms and AI model-serving services, owning products end to end — from design through production operations.
  • Built and operate OpenGateway, an LLM API gateway handling 250K+ daily calls across 10+ providers; also shipped AI integration and payment backends at Wrtn and Kurly Pay.
  • Pragmatic about technology choices, biased toward shipping fast, and focused on stabilizing systems in production.

Experience

See full portfolio.

Sionic AI

Backend Developer
  • Built and operate OpenGateway, an LLM API gateway serving 250K+ daily calls (RPM 180) across 10+ providers and 100+ models, with multi-deployment support.
  • Launched Storm Parse as a public API product in two weeks, driving the company's first external SaaS revenue.
  • Developed operational tooling and standardized workflows (API Hub, test and back-office tools), improving team productivity.

Wrtn Technologies

Backend Developer
  • Built an AI model-serving service on Spring AI (RPM 750), cutting API response time 20% while improving observability and stability.
  • Migrated an existing Node.js service to the JVM with zero downtime.
  • Shipped company-wide shared services: tokenizer, email validation, and profanity detection.

Kurly Pay

Backend Developer
  • Led Kurly Pay gift cards from design through operations, including the B2C/B2B bulk-send process.
  • Expanded sales channels through partner integrations; supported payment migration and prepaid/points design.

Earlier Experience

Backend Developer / SI Development
  • B2B platform development at Marketboro · mobile web, admin, and part-time app development at earlier startups
  • SI and IT operations at Kakao Pay, FirstData Korea, and Hana INS

Education

  • Kwangwoon University B.S. in Computer Software, GPA 3.29 / 4.5