Show HN: Korea-data-MCP – Korean public APIs that agents can't misread

A developer released korea-data-mcp, an open-source MCP server that wraps the official free APIs of OpenDART, data.go.kr and law.go.kr so AI agents return correct answers on Korean corporate filings, stock prices, apartment sale prices, business registration status, public holidays, statutes and court rulings. The server handles 47 documented traps found on the live APIs, each covered by a test using the real response — including OpenDART's half-year revenue field, where an agent reading the period-labeled field would report Samsung Electronics' first-half 2025 revenue as ₩74.6 trillion instead of the correct ₩153.7 trillion, and law.go.kr's inclusion of promulgated-but-not-in-force text such as Labor Standards Act 제44조의4, which the API labels effective 2026-10-08 but which takes effect 2027-01-01. The project ships as a single binary installable in one click via korea-data-mcp.mcpb in Claude Desktop and is listed in the official MCP Registry, runs locally with no telemetry, and exposes 15 tools.

English | 한국어 https://github.com/YoungsoonLee/korea-data-mcp/blob/main/README.ko.md Pass Korean public APIs straight to an AI agent and it gets answers wrong. korea-data-mcp gives it the right ones. An MCP server for Korean corporate filings and financials, stock prices, apartment sale prices, business registration status, public holidays, statutes and court rulings, from the official free APIs of OpenDART, data.go.kr and law.go.kr. - Correct, with evidence. 47 traps found on the live APIs wrong half-year revenue, laws not in force yet, cancelled deals, district codes that changed in 2026, and more are handled, each covered by a test that uses the real response. The full list is public: What korea-data-mcp handles for you https://github.com/YoungsoonLee/korea-data-mcp/blob/main/docs/QUIRKS.md . - Installs in one click. A single binary with nothing else to install. In Claude Desktop, open korea-data-mcp.mcpb https://github.com/YoungsoonLee/korea-data-mcp/releases/latest/download/korea-data-mcp.mcpb and enter your keys. Also in the official MCP Registry https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.YoungsoonLee/korea-data-mcp . - Private. It runs on your machine. Your keys and questions go only to the government APIs, never through a third-party server, and there is no telemetry. - Focused. 15 tools with clear descriptions, so an agent picks the right one without filling its context with dozens of others. Example: "What was Samsung Electronics' revenue in the first half of 2025?" Here is what OpenDART actually returns: { "account nm": "매출액", "thstrm dt": "2025.01.01 ~ 2025.06.30", "thstrm amount": "74,566,317,000,000", "thstrm add amount": "153,706,820,000,000" } The period says January to June, so an agent reads thstrm amount and answers ₩74.6 trillion. That is wrong : it is the second quarter only. The half-year figure, ₩153.7 trillion, is in a different field. Most Korean MCP servers pass this response on as is. korea-data-mcp returns: { "name": "매출액", "statement type": "income statement", "current period": "2025-01-01 ~ 2025-06-30", "current amount": 153706820000000, "current quarter amount": 74566317000000 } So the agent gets it right, and can even split out the second quarter: Three more traps, each of which silently produces a wrong answer: - Law that is not law yet. Ask law.go.kr for the current Labor Standards Act 근로기준법 and the text includes 제44조의4, labeled as in effect since 2026-10-08. It actually takes effect on 2027-01-01 ; the official "current law" text already contains amendments that are only promulgated. korea-data-mcp returns the text in force on the date you ask for today by default and lists what is coming in upcoming tool output shortened :- Deals that never happened. Apartment trade data keeps cancelled deals, marked only by a flag: 12 of 233 Gangnam trades in September 2025, including a ₩7.5 billion one. Averages that include them are wrong. korea-data-mcp leaves them out. - Codes that quietly stop working. In 2026, 광주광역시 and 전라남도 merged, 화성시 was split into four 구, and 인천 reorganized its districts. The old district codes, which most code tables still list, now return zero trades, even for past months . With korea-data-mcp, an agent just says 광주 북구 or 화성시 . There is more: errors returned as HTTP 200, stale records mixed with current ones, business numbers that fail when written with hyphens, stock history split by a company rename, and a TLS handshake that fails from Go. See all 47: What korea-data-mcp handles for you https://github.com/YoungsoonLee/korea-data-mcp/blob/main/docs/QUIRKS.md . Connect korea-data-mcp to Claude or any MCP client and ask in English or Korean: - "What was Samsung Electronics' revenue in the first half of 2025, and what has it disclosed recently?" - "What was the median apartment sale price in 분당구 in September 2025?" - "Is 제44조의4 of the Labor Standards Act 근로기준법 in force yet?" - "Find recent Supreme Court rulings on unfair dismissal 부당해고 and summarize the holding of the latest one." - "Is business registration number 124-81-00998 still active?" - "How did NAVER's stock price move last month?" - "Which public holidays are left in Korea this year?" | Source | What it covers | Key | |---|---|---| | OpenDART https://opendart.fss.or.kr 전자공시 | Company profiles, disclosures, financial statements of ~120,000 companies | OPENDART API KEY | | data.go.kr https://www.data.go.kr 공공데이터포털 | Holidays, corporation info, business status, apartment trades, stock prices | DATAGOKR SERVICE KEY | | law.go.kr https://open.law.go.kr 국가법령정보 | Statutes as in force on any date, court rulings | LAWGOKR OC | All three keys are free. You can start with just one. Claude Desktop, in one click: download korea-data-mcp.mcpb https://github.com/YoungsoonLee/korea-data-mcp/releases/latest/download/korea-data-mcp.mcpb , open it or drag it into Settings → Extensions , and enter the keys you have how to get them api-keys . Nothing else to install; skip to step 4 4-check-it . Download a binary for macOS, Linux or Windows Intel or ARM from Releases https://github.com/YoungsoonLee/korea-data-mcp/releases/latest , extract it, and note the absolute path of korea-data-mcp korea-data-mcp.exe on Windows . For example, on an Apple Silicon Mac: curl -L https://github.com/YoungsoonLee/korea-data-mcp/releases/latest/download/korea-data-mcp darwin arm64.tar.gz | tar xz ./korea-data-mcp -version On macOS, a binary downloaded with a browser is blocked as coming from an unidentified developer; run xattr -d com.apple.quarantine korea-data-mcp once. curl downloads are not affected. Or with Go 1.26 or later Go 1.21+ downloads the right toolchain automatically : go install github.com/YoungsoonLee/korea-data-mcp/cmd/korea-data-mcp@latest The binary is installed to $ go env GOPATH /bin/korea-data-mcp . Start with OpenDART : sign up at opendart.fss.or.kr https://opendart.fss.or.kr , request a key 인증키 신청 , and it is issued right away. For all three, step by step with the Korean menu names: Getting API keys https://github.com/YoungsoonLee/korea-data-mcp/blob/main/docs/KEYS.md . Any subset works; tools whose key is missing are simply not offered. Outside Korea? These portals usually require Korean identity verification a Korean mobile number to sign up, so getting keys from abroad can be hard or impossible. A hosted version that needs no keys of your own is planned: join the waitlist https://github.com/YoungsoonLee/korea-data-mcp/issues/new?template=hosted-access.yml . Use absolute paths. Leave out the keys you don't have. Claude Code: claude mcp add korea-data-mcp \ -e OPENDART API KEY=... \ -e DATAGOKR SERVICE KEY=... \ -e LAWGOKR OC=... \ -- /absolute/path/to/korea-data-mcp Claude Desktop: edit ~/Library/Application Support/Claude/claude desktop config.json macOS or %APPDATA%\Claude\claude desktop config.json Windows , then restart Claude Desktop: { "mcpServers": { "korea-data-mcp": { "command": "/absolute/path/to/korea-data-mcp", "env": { "OPENDART API KEY": "...", "DATAGOKR SERVICE KEY": "...", "LAWGOKR OC": "..." } } } } Other MCP clients take the same command and environment variables. To keep keys in one file instead, copy .env.example https://github.com/YoungsoonLee/korea-data-mcp/blob/main/.env.example to .env , fill it in, and pass -env-file /absolute/path/to/.env as an argument. A variable set in the environment takes precedence over the file. Ask your agent "Which korea-data-mcp providers are enabled?". It calls hub list providers , which lists the enabled providers and any missing keys. Then try one of the questions above what-you-can-ask . Step-by-step instructions and troubleshooting: Getting API keys https://github.com/YoungsoonLee/korea-data-mcp/blob/main/docs/KEYS.md . All three are free, but signing up usually requires Korean identity verification. If you can't get them, join the hosted waitlist https://github.com/YoungsoonLee/korea-data-mcp/issues/new?template=hosted-access.yml . | Environment variable | Source | How to get it | |---|---|---| | OPENDART API KEY | OpenDART | opendart.fss.or.kr https://opendart.fss.or.kr → 인증키 신청 request a key | | DATAGOKR SERVICE KEY | data.go.kr | data.go.kr https://www.data.go.kr → sign up → apply for each API 활용신청; links in Tools tools → My Page | | LAWGOKR OC | law.go.kr | open.law.go.kr https://open.law.go.kr → OPEN API 신청 apply → 마이페이지 → API인증키관리 OC | data.go.kr : The portal issues two keys, Encoding and Decoding. Use the Decoding key . The Encoding key gets URL-encoded twice and fails with SERVICE KEY IS NOT REGISTERED ERROR . One key covers every API you apply for. law.go.kr : The OC is a value you choose under 마이페이지 → API인증키관리. A wrong OC gives the error "사용자 정보 검증에 실패하였습니다". law.go.kr puts the OC in every link it returns, so don't reuse another key as the OC korea-data-mcp never passes those links on . OpenDART OPENDART API KEY | Tool | What it does | |---|---| | opendart search companies | Find a company's corp code by Korean/English name, stock code, or corp code | | opendart get company | Company profile 기업개황 : CEO, market, registration numbers, address, fiscal year-end | | opendart search disclosures | Search disclosures 공시 by company, date range, type, and market | | opendart get financials | Key financial accounts 주요계정 for a year and report, with prior-period comparisons | Every OpenDART tool that takes corp code also accepts a 6-character stock code e.g. 005930 . data.go.kr DATAGOKR SERVICE KEY . Each API needs its own application 활용신청 on data.go.kr; the links are below. | Tool | What it does | API to apply for | |---|---|---| | datagokr list holidays | Public holidays 공휴일 for a year or month, including substitute holidays, Seollal and Chuseok, and election days, with English names and weekdays. Also anniversaries, the 24 solar terms, and seasonal days. 2004 through two years ahead | 한국천문연구원 특일 정보 https://www.data.go.kr/data/15012690/openapi.do | | datagokr search corporations | Find Korean corporations by name, listed or not. Returns the corporate registration number crno and, for DART filers, dart corp code for opendart tools | 금융위원회 기업기본정보 https://www.data.go.kr/data/15043184/openapi.do | | datagokr get corporation | Current company profile: CEO, market, registration numbers, founding and listing dates, address, industry, employees, average tenure and salary, auditor and audit opinion | Same as above | | datagokr check business status | Check up to 100 business registration numbers 사업자등록번호 with the National Tax Service: registered or not, active, suspended or closed with date , and VAT type. Hyphens are fine | 국세청 사업자등록정보 진위확인 및 상태조회 https://www.data.go.kr/data/15081808/openapi.do | | datagokr list apartment trades | Apartment sale transactions for a district and month, newest first, with a median/min/max price summary. Prices in KRW; cancelled deals excluded by default; filter by apartment name or neighborhood. The region is a name 강남구 , 서울 중구 , 분당구 , 광주 북구 or a 5-digit code; a city with wards, such as 수원시 or 화성시 , covers all of them | 국토교통부 아파트 매매 실거래가 자료 https://www.data.go.kr/data/15126469/openapi.do | | datagokr get stock prices | Daily prices of a KOSPI, KOSDAQ or KONEX stock: close, change, open/high/low, volume, trading value, market cap. The stock is a name 삼성전자 , naver , a 6-digit code or an ISIN; history follows the code across renames. Since 2020 | 금융위원회 주식시세정보 https://www.data.go.kr/data/15094808/openapi.do | law.go.kr LAWGOKR OC | Tool | What it does | |---|---| | lawgokr search laws | Search statutes in force acts, decrees, ordinances by name or official abbreviation 민법 , 중대재해처벌법 , or by article text with in text . Exact matches and acts first | | lawgokr get law | The text of a statute as in force on a date default today , whole or one article 제50조 , 43의2 , with paragraphs, subparagraphs and items. Lists promulgated amendments that take effect later in upcoming ; any past or future date works with as of | | lawgokr search precedents | Search court rulings 판례 , newest first, by case name, full text, case number 2020다296604 , spaces are fine , court and decision date. Court records only by default, so every result can be read | | lawgokr get precedent | A ruling by id or case number: issues 판시사항 , holding 판결요지 , cited statutes and cases, and the full decision with include full text | Hub : hub list providers lists the enabled providers and the keys that are missing. - Your keys stay on your machine. korea-data-mcp runs locally and sends each key only to the service that issued it. There is no telemetry. Error messages never include keys or query strings. - HTTP mode has no authentication. -http serves the tools to anyone who can reach the port, using your keys. Bind it to localhost -http 127.0.0.1:8080 unless it is behind an authenticating proxy. The default stdio mode does not open a port. - Upstream quotas apply. A data.go.kr development account allows 10,000 calls per day for each API; OpenDART and law.go.kr have their own limits. korea-data-mcp caches responses for 10 minutes and the DART company list for 24 hours. - Data is as fresh as the source. Apartment deals can be reported up to 30 days after the contract, so the latest month fills in over time. Stock prices are daily, updated after each trading day. - OpenDART: companies, disclosures, financials - data.go.kr: holidays, corporation info, business status, apartment trades, stock prices - law.go.kr: statutes, court rulings - Bank of Korea ECOS, KOSIS Korean Statistical Information Service - A sibling server for Japan, starting with EDINET corporate disclosures Want a data source added? Request it https://github.com/YoungsoonLee/korea-data-mcp/issues/new?template=data-source.yml . Found an API behaving oddly? Open an issue https://github.com/YoungsoonLee/korea-data-mcp/issues . No Korean API keys? Join the hosted waitlist https://github.com/YoungsoonLee/korea-data-mcp/issues/new?template=hosted-access.yml . To build, test or add a provider, see docs/DEVELOPMENT.md https://github.com/YoungsoonLee/korea-data-mcp/blob/main/docs/DEVELOPMENT.md . Apache License 2.0 https://github.com/YoungsoonLee/korea-data-mcp/blob/main/LICENSE . Data returned by the tools comes from the upstream services and is subject to their terms of use.