DUNS Number

GET/v0/duns

Validates DUNS (Data Universal Numbering System) numbers — 9-digit company identifiers issued by Dun & Bradstreet. Widely required in public procurement, US federal contracting, and international trade. Accepts both plain format (150483782) and hyphenated format (15-048-3782). Optionally performs a live lookup against the D&B Direct+ API to retrieve company details.

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Query Parameters

Parameter	Type	Required	Description
value	string	Yes	The 9-digit DUNS number to validate. Hyphens and spaces are ignored (e.g. `00-668-9579` and `006689579` are equivalent).
lookup	boolean	No	When `true`, performs a live lookup against the D&B Direct+ API and returns company details.

Example Request

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/duns?value=006689579&lookup=true"

Response Fields

Field	Type	Description
valid	boolean	Whether the value is a valid 9-digit DUNS number
formatted	string	The number in canonical hyphenated format (`XX-XXX-XXXX`). Only present when `valid` is `true`.
duns	object	Live lookup result. Present only when `lookup=true`. See The `duns` object below.

The `duns` object

When the lookup failed (checked: false):

Field	Type	Description
checked	boolean	`false`
reason	string	`unavailable` — the D&B Direct+ API could not be reached or credentials are not configured

When the lookup succeeded (checked: true):

Field	Type	Description
checked	boolean	`true`
found	boolean	Whether the company was found in the D&B registry
name	string \| null	Registered company name
countryCode	string \| null	ISO 3166-1 alpha-2 country code of the registered address
city	string \| null	City of the registered address
region	string \| null	State or region abbreviation (e.g. `NY`, `CA`)
postalCode	string \| null	Postal code of the registered address
street	string \| null	Street address line
isActive	boolean \| null	Whether the company is currently active. `null` if status is unknown.

Example Response

{
  "valid": true,
  "formatted": "00-668-9579",
  "duns": {
    "checked": true,
    "found": true,
    "name": "Dun & Bradstreet Inc.",
    "countryCode": "US",
    "city": "Jacksonville",
    "region": "FL",
    "postalCode": "32202",
    "street": "5335 Gate Pkwy",
    "isActive": true
  }
}