Korean Stock Data (aikstockdata)

aikstockdata is a free, keyless JSON data service for the Korean stock market. Every trading day it publishes closing prices, volume and market cap for 2,791 KOSPI and KOSDAQ stocks it covers, the KOSPI and KOSDAQ index levels, a year of daily price history per stock, DART regulatory filings with plain-language explanations, and quarterly earnings extracted from those filings. There's no signup, no API key and no request quota, and CORS is open, so a browser app can call it directly.

The problem it solves is access. Korean market data sits behind broker feeds and paid vendors, and the public sources, the Financial Services Commission's open data and the Financial Supervisory Service's DART filing system, are official but awkward to consume from code. That matters for anyone outside Korea in particular, since the official sources assume a Korean reader and a Korean workflow, and the paid vendors assume a professional budget. aikstockdata collects from those public sources, cleans and structures the result, and republishes it as self-describing JSON that a developer or an AI tool can read without a Korean brokerage account.

The interesting layer is what it does with filings. Each DART filing carries its receipt time to the minute in Korean time, and the service tracks what happened next, publishing a market-adjusted median return at one, five and twenty days after a filing so you can see how the market has historically reacted to that kind of disclosure. There's a daily digest, rankings, a filing briefing, an earnings calendar and a watch list view, all backed by the same JSON. Failures in the pipeline are logged publicly, and missing values are distinguished from zeros rather than silently filled.

The site is organised around how people read markets rather than around endpoints. There's a filing briefing that summarises the day's disclosures, an earnings announcements view, an earnings calendar, a watch list of stocks under observation, a downloads area for bulk files and a community board. Every day's publication carries a status line with the settlement date of the prices, when the collection ran and when the next refresh is due, so you always know how fresh the snapshot is. The design goal, stated on the homepage, is data that's easy for an AI to read, and the JSON is self-describing with that in mind.

It's built for developers, researchers, quant hobbyists and anyone wiring an AI assistant up to Korean equities. Access comes three ways. An MCP server lets you paste one URL into Claude or ChatGPT and ask about Korean stocks mid-conversation. REST style endpoints with an OpenAPI 3.1 specification serve code. And a catalog index plus sample records let you inspect the shape of the data, with Samsung Electronics as the worked example. The data is also mirrored on GitHub and as a Hugging Face dataset.

A first session is short. Open the catalog file to see what's published, fetch the Samsung Electronics record to see the shape of a single stock, then either wire the endpoints into code using the OpenAPI document or paste the MCP URL into your assistant and start asking questions. Because the files are static, a nightly job that mirrors what you need is trivial to write and won't hit a quota.

What makes it different from a broker API is the posture. It's end of day, not real time, prices are the previous business day's official close, and the whole thing is published as static JSON over HTTPS after the close on every trading day, at ten past six in the evening Korean time. That's a deliberate trade. You lose intraday quotes and gain something reproducible, cacheable and free that doesn't fall over when a key expires.

The limits are clear on the site. It covers the stocks it collects rather than the entire listed market, there are no real-time quotes, no analyst ratings and no sector classifications, and the filing explanations are in Korean, so non-Korean readers will lean on the structured fields. The service describes itself as a snapshot, not a feed, and the homepage repeats that prices aren't real time in more than one place, so nobody should build a trading tool on it expecting intraday data. The site itself is primarily Korean with an English entry page and English endpoint documentation.

Access is free, including commercial use, provided you credit Korean Stock Data (aikstockdata.com) and the original public sources. Attribution is the only condition. Redistributing real-time broker data is prohibited by the terms. No contact email is published, but the GitHub and Hugging Face pages are the public channels.