CEIDG (Poland)

GET/v0/pl/ceidg

Validates Polish NIP numbers and optionally looks up the entity in the CEIDG register (Centralna Ewidencja i Informacja o Działalności Gospodarczej — Central Registration and Information on Business Activity). CEIDG covers sole proprietors and civil partnerships (spółki cywilne) only — companies registered in the KRS (sp. z o.o., S.A., etc.) are not present. Validation uses the official NIP checksum algorithm (weighted sum mod 11). Input may include hyphens or spaces — they are ignored before validation.

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Query Parameters

Parameter	Type	Required	Description
value	string	Yes	The NIP number to validate (10 digits). Hyphens and spaces are ignored (e.g. `526-104-08-28` and `5261040828` are equivalent).
lookup	boolean	No	When `true`, performs a live lookup against the official Polish CEIDG government API and returns entity details.

Example Request

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/pl/ceidg?value=5261040828&lookup=true"

Response Fields

Field	Type	Description
valid	boolean	Whether the NIP checksum is correct
nip	string	NIP in canonical hyphenated format (`NNN-NNN-NN-NN`). Only present when `valid` is `true`.
ceidg	object	Live lookup result. Present only when `lookup=true`. See The `ceidg` object below.

The `ceidg` object

When the lookup failed (checked: false):

Field	Type	Description
checked	boolean	`false`
reason	string	`unavailable` — the CEIDG API could not be reached or the API key is not configured

When the lookup succeeded (checked: true):

Field	Type	Description
checked	boolean	`true`
found	boolean	Whether the entity was found in the CEIDG register
status	string \| null	Registration status: `active`, `suspended`, or `deleted`
firstName	string \| null	First name of the owner
lastName	string \| null	Last name of the owner
businessName	string \| null	Registered business name
regon	string \| null	Statistical identification number (REGON)
city	string \| null	City of the registered business address
postalCode	string \| null	Postal code
street	string \| null	Street name
houseNumber	string \| null	Building/house number
flatNumber	string \| null	Flat/apartment number
startDate	string \| null	Date of business commencement (ISO 8601, YYYY-MM-DD)
pkd	string[]	All PKD codes (Polish Classification of Activities) registered for this entity. Use `GET /v0/pl/pkd` to decode each code into its full name and hierarchy.
primaryPkd	string \| null	Primary (predominant) PKD code

Example Response

{
  "valid": true,
  "nip": "526-104-08-28",
  "ceidg": {
    "checked": true,
    "found": true,
    "status": "active",
    "firstName": "Jan",
    "lastName": "Kowalski",
    "businessName": "JK CONSULTING JAN KOWALSKI",
    "regon": "147123456",
    "city": "Warszawa",
    "postalCode": "00-001",
    "street": "Marszałkowska",
    "houseNumber": "1",
    "flatNumber": "2",
    "startDate": "2015-03-01",
    "pkd": ["70.22.Z", "74.90.Z", "63.11.Z"],
    "primaryPkd": "70.22.Z"
  }
}