x402 · USDC on Base

Korean holidays, business days & Hangul utilities for AI agents

Models trained before 2026 don't know that South Korea made 노동절 (May 1) and 제헌절 (Jul 17) public holidays, or how 대체공휴일 substitute rules differ by holiday. KoreaKit answers these questions deterministically and cheaply. No signup and no API key: an agent pays per call over HTTP 402.

Endpoints

GETWhat it doesPrice
/v1/holidaysAll Korean public holidays of a year
year		$0.003
/v1/holidays/checkIs a date a Korean public holiday / business day?
date		$0.003
/v1/business-days/addAdd or subtract Korean business days
date days		$0.003
/v1/business-days/countCount Korean business days between two dates
from to		$0.003
/v1/lunar/to-solarKorean lunar date → Gregorian
date leap?		$0.003
/v1/lunar/from-solarGregorian → Korean lunar date
date		$0.003
/v1/text/amountNumber → Korean amount in words (금액 한글 표기)
n		$0.003
/v1/text/josaPick the right Korean particle (조사) for a word
word josa		$0.003
/v1/text/romanizeHangul → Revised Romanization
text mode?		$0.003
/v1/validate/brnValidate a Korean business registration number (사업자등록번호)
number		$0.003

How to call

curl -i "https://koreakit.celee.workers.dev/v1/holidays/check?date=2026-05-01"
# → 402 + PAYMENT-REQUIRED header (x402 v2). Any x402 client pays and retries:
#   network eip155:8453, asset USDC, scheme "exact".

Use an x402-capable client (e.g. @x402/fetch, Coinbase AgentKit, or an MCP wallet). Bad parameters return a free 400, so you only pay for successful answers. Machine-readable docs: /llms.txt, /openapi.json.

Example: /v1/holidays/check?date=2026-05-01

{
  "date": "2026-05-01",
  "weekday": "Fri",
  "is_holiday": true,
  "is_weekend": false,
  "is_business_day": false,
  "holidays": [
    {
      "date": "2026-05-01",
      "weekday": "Fri",
      "name": "노동절",
      "name_en": "Labor Day",
      "type": "public"
    }
  ],
  "meta": {
    "as_of": "2026-10-28",
    "basis": "공휴일에 관한 법률 · 관공서의 공휴일에 관한 규정 (incl. 2026 노동절·제헌절, 대체공휴일 rules)",
  …

무료 도구 (사람용)

영업일 계산기 · 금액 한글 변환기

2025년 공휴일2026년 공휴일2027년 공휴일2028년 공휴일

한국 공휴일·대체공휴일·영업일 계산, 음양력 변환, 금액 한글 표기, 조사 선택, 사업자등록번호 검증, 로마자 표기를 API로 제공합니다. 근거: 공휴일에 관한 법률, 관공서의 공휴일에 관한 규정, 한국천문연구원 음력 자료.