# K-Data x402

> Korean market data for AI agents — kimchi premium on a tradeable USDT basis, premium history and percentiles, Korean news translated to English, Upbit KRW quotes. Pay per request with USDC via x402. No account, no API key.

Payment: x402 protocol (HTTP 402), scheme "exact", USDC on Base mainnet.
No account or API key needed. Use any x402 client (e.g. @x402/fetch) to pay per request.

## Why this service

- Dual-basis kimchi premium: the official USD/KRW figure everyone quotes, plus the Upbit KRW/USDT basis that an arbitrageur can actually realize. The two often disagree in sign — official can read negative while the tradeable basis is positive.
- Premium history and percentile context, continuously archived. No free source and no competing x402 seller offers this; it cannot be reconstructed after the fact.
- Korean headlines translated to English, so a non-Korean agent can actually use them.

## Paid endpoints

- [GET /api/kimchi-premium](https://k-data-x402-production.theblack1022.workers.dev/api/kimchi-premium) ($0.03): Kimchi premium on two bases: premium_official_pct (official USD/KRW rate — the quoted figure) and premium_usdt_pct (Upbit KRW/USDT rate — the margin actually realizable, since the KRW exit leg goes through USDT rather than banks). The two frequently disagree in sign. Optional ?symbols=BTC,ETH (max 10).
- [GET /api/kimchi-premium/stats](https://k-data-x402-production.theblack1022.workers.dev/api/kimchi-premium/stats) ($0.12): Where the current kimchi premium sits inside its own recent distribution: percentile, mean, stdev, z-score, min/max/median, and a plain-language read. Answers 'is this premium unusual right now?' in one call. Built from a continuous archive that cannot be reconstructed from any free source. Params: ?symbol=BTC &window=1h|6h|24h|7d|30d|90d &basis=usdt|official.
- [GET /api/kimchi-premium/history](https://k-data-x402-production.theblack1022.workers.dev/api/kimchi-premium/history) ($0.08): Time series of the kimchi premium from the continuous archive, both bases, newest-last. Params: ?symbol=BTC &window=1h|6h|24h|7d|30d|90d &points=500 (max 2000). Archive depth is reported as first_recorded.
- [GET /api/news/headlines/en](https://k-data-x402-production.theblack1022.workers.dev/api/news/headlines/en) ($0.05): Latest Korean headlines with English translations attached (title_en), from Yonhap, Maeil Business and Hankyung — deduplicated, newest first. Use this instead of the Korean-only route when the consuming agent does not read Korean. Optional ?category=top|economy|tech|politics and ?limit=20 (max 50).
- [GET /api/korea/market-snapshot](https://k-data-x402-production.theblack1022.workers.dev/api/korea/market-snapshot) ($0.08): One-call Korea briefing: dual-basis kimchi premium + top Upbit KRW markets + USD/KRW + latest economy headlines translated to English. Everything needed for a Korea market read in a single paid request.
- [GET /api/crypto/krw/markets](https://k-data-x402-production.theblack1022.workers.dev/api/crypto/krw/markets) ($0.01): Snapshot of all Upbit KRW crypto markets: top by 24h traded value, top gainers, top losers. Optional ?limit=30 (max 100) for the volume ranking.
- [GET /api/news/headlines](https://k-data-x402-production.theblack1022.workers.dev/api/news/headlines) ($0.01): Latest Korean headlines from Yonhap, Maeil Business and Hankyung, deduplicated and newest-first. Titles stay in Korean — use /api/news/headlines/en for English. Optional ?category=top|economy|tech|politics and ?limit=30 (max 100).
- [GET /api/crypto/krw/:ticker](https://k-data-x402-production.theblack1022.workers.dev/api/crypto/krw/:ticker) ($0.005): Live quote for one Upbit KRW market by ticker symbol (e.g. BTC, ETH, XRP): price, 24h change, 24h high/low, 24h traded value in KRW.
- [GET /api/fx/usdkrw](https://k-data-x402-production.theblack1022.workers.dev/api/fx/usdkrw) ($0.005): Current USD/KRW exchange rate (ECB reference via Frankfurter, fallback open.er-api.com).

## Free endpoints

- [GET /openapi.json](https://k-data-x402-production.theblack1022.workers.dev/openapi.json): OpenAPI 3.1 spec with per-endpoint pricing
- [GET /api/catalog](https://k-data-x402-production.theblack1022.workers.dev/api/catalog): machine-readable catalog with schemas and examples