Data guide

What is in here, where each value came from, and how complete it is — including the parts that are thin.

Scope

Companies	152,367
Who is included	Korean for-profit corporate headquarters with 10 or more insured employees, identified from employment-insurance workplace records
Who is not	Sole proprietors, branches, non-profits, and companies under 10 insured employees. A registration number outside this set is not necessarily invalid
Employment history	36 months, monthly

Coverage by field

Measured across all 152,367 companies, not a sample.

Field	Present	Source
Employees (Employment Insurance)	100.0%	Workers' Compensation & Welfare Service
Address in English	100.0%	Rendered by rule
Established date	100.0%	FSC, else insurance inception
Worksite count	100.0%	Workers' Compensation & Welfare Service
Monthly employment series	83.3%	National Pension Service
Corporate registration number	70.5%	Financial Services Commission
Phone	69.3%	Financial Services Commission
Listing market · DART code	25.5%	Financial Services Commission
Homepage	18.3%	Financial Services Commission

10,284 companies (6.7%) have neither a Financial Services Commission match nor a pension link. For those, the record is employees, address, an insurance-inception date and a worksite count. It is thin, but no record is empty.

Sources and how often they change

Source	Gives	As of	Refresh
Korea Workers' Compensation & Welfare Service	Company and worksite master, employment-insurance headcount, industry code	2025-12-31	Annual
National Pension Service	Monthly subscriber counts, hires, separations	2026-07	Monthly
National Tax Service	Registration status (active, suspended, closed)	Per record	Weekly
Financial Services Commission	Corporate registration number, incorporation date, contact, listing	Per record	Daily
Statistics Korea	KSIC 11th industry names in official English	—	Rare

Fields that mean less than they look like

Three fields carry a companion field saying what kind of value it is. Read them together.

`name_en_class`	`official` — the English name registered with the Financial Services Commission. `generated` — romanized from Korean by rule. It is a reading aid, not a registered name. Do not use it as a legal name.
`established_date_source`	`fsc_estb` — the incorporation date. `insurance_inception` — the date the company first enrolled in employment insurance. These are different facts and we do not blur them into one "founded" field.
`nps_quality`	A company can run several worksites, and pension records are per worksite. When we sum them we say how confident the sum is: `clean`, `review`, `contaminated`, `unknown`. `clean` means no sign of double counting — it is not a verification.

Two employee numbers, on purpose

`ei_workers`	Employment Insurance enrollees. Annual, from the master file.
`nps_latest`	National Pension subscribers in `nps_period`. Monthly. Excludes subscribers aged 60 and over and includes registered directors, so it differs from the insurance figure by design.

We do not reconcile them into a single "headcount". They are two government counts of two different things, and the gap between them is information.

What this dataset does not do

No assessment	No score, no grade, no ranking, no opinion about any company. We state facts and where they came from.
No negative records	No sanctions, penalties, litigation or industrial-accident history. Not "coming later" — out of scope by design.
No people	No representative names, no personal contact details. Company records only.
No inference	Nothing is modelled, imputed or estimated. If a value is absent, it is absent, and the record says so.

Known limits

Pension records are linked by registration number and normalized company name. 83.3% of companies link; the rest have no monthly series.
Where a company has several same-named worksites, the sum is flagged rather than silently trusted — see nps_quality.
English addresses are rendered by rule to the government English format. They have not been checked against the official English address database.
The master file refreshes annually, so ei_workers and the worksite list move once a year. The pension series is where recent movement shows up.

API & MCP docs Get a key — 50 free credits