The data nobody sells: why I started taking a daily snapshot of 211,243 companies
Korea's National Tax Service runs a clean public API for business registration status. Give it a 10-digit number, get back whether the company is active, suspended or closed. It's free, it's fast, it's accurate. It also has no memory. Ask it today and you learn the company is closed. Ask what it was last month and there's no answer, because that question isn't in the API. There's no as_of…
Korea's National Tax Service offers a free, fast, and accurate public API for checking a company's registration status with a 10-digit number. This data is current-only, meaning it only reveals the status at the moment of the query, with no historical context provided. The author of the source noticed this limitation while building an API for AI agents and decided to manually track the status changes of 211,243 companies daily.
The process involved a scheduled job that queried the API for each company's status, stored the results, and compared them against the previous day's data to identify any changes. Over the course of three days, the author observed 94 out of 211,243 observations, or 0.04%, as changes. The changes are stored with timestamps indicating when the change was first seen and when it was detected.
This data collection is valuable because it cannot be obtained from any other source and provides insights that are not available through single-point lookups. The author emphasizes the importance of starting the data collection process immediately, rather than waiting for a specific need, as the historical data accumulated will be unique and irreplaceable.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
