I Built a Korean AI API With $0 and It Makes Money While I Sleep

The Problem

There are 80+ million Korean speakers worldwide, and thousands of businesses need to process Korean text — news monitoring, K-content translation, market research, social media analysis.

But most translation APIs treat Korean as an afterthought. Google Translate is decent for simple sentences, but fails on:

• Business Korean (formal/informal register)


• Korean slang and internet language


• Context-dependent meaning


• Summarizing Korean text into English

What I Built

Korean AI Translator & Analyzer — a REST API with 3 endpoints:

1. /translate — Korean ↔ English

Not word-by-word. AI-powered, context-aware translation.

POST /translate

{

  "text": "오늘 날씨가 정말 좋다. 커피 한 잔 하면서 코딩하기 딱 좋은 날이야.",

  "direction": "auto"

}



// Response:

{

  "translated_text": "The weather is really great today. It's a perfect day to have a cup of coffee and do some coding.",

  "source_language": "ko",

  "target_language": "en"

}

2. /summarize — Summarize Korean text in English

Feed it a Korean news article, get an English summary.

POST /summarize

{

  "text": "삼성전자가 차세대 HBM4 메모리 반도체의 양산을 시작했다...",

  "language": "en",

  "max_sentences": 2

}



// Response:

{

  "summary": "Samsung Electronics has begun mass production of HBM4 memory, which is 2x faster and 30% more power-efficient. Supply confirmed to both NVIDIA and AMD.",

  "original_length": 189,

  "summary_length": 168

}

3. /analyze — Sentiment + Keywords + Category

Understand Korean text without reading Korean.

POST /analyze

{

  "text": "삼성전자 주가가 급등했다. HBM4 메모리 칩이 엔비디아에 공급 확정."

}



// Response:

{

  "sentiment": "positive",

  "confidence": 0.85,

  "keywords": ["삼성전자", "HBM4", "엔비디아"],

  "category": "economy",

  "summary_en": "Samsung Electronics stock surged on HBM4 supply confirmation to NVIDIA."

}

The Stack (Total Cost: $0)

No servers to manage. No AI bills. No infrastructure costs.

How It Makes Money

Listed on RapidAPI with a freemium model:

RapidAPI handles billing, authentication, and rate limiting. I just built the API.

Who Needs This?

• 
  Trading firms monitoring Korean market news


• 
  K-content platforms translating K-pop/K-drama content


• 
  Marketing agencies analyzing Korean social media


• 
  News aggregators covering Asian markets


• 
  Researchers studying Korean media

Try It

• 
  RapidAPI:
  

Also built an MCP server for Claude users: korean-news-mcp — gives Claude real-time access to Korean news.

What I Learned

1. 
   Niche beats broad. 282 translation APIs on RapidAPI, but almost none specialize in Korean.


2. 
   AI APIs are basically free to run. Groq gives 14,400 free requests/day. Vercel's free tier handles the rest.


3. 
   Build the API, let the marketplace sell it. RapidAPI has millions of developers browsing. I don't need to do marketing — I need to be findable.

Built in one day with Python, FastAPI, and Claude Code. Total investment: $0.