ABN

GET/v0/au/abn

Validates an Australian Business Number (ABN) — the 11-digit identifier issued by the Australian Business Register (ABR) to all entities registered in Australia. The check digit is verified using a weighted modulus-89 algorithm. Spaces and hyphens in the input are stripped automatically. Optionally looks up business details from the ABR government API.

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Query Parameters

Parameter	Type	Required	Description
value	string	Yes	The 11-digit ABN (e.g. `51 824 753 556`)
lookup	string	No	Set to `true` or `1` to look up business details from the Australian Business Register (ABR)

Example Request

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/au/abn?value=51824753556"

Response Fields

Field	Type	Description
valid	boolean	Whether the ABN passed modulus-89 checksum validation
abn	string	The normalized 11-digit ABN
formatted	string	ABN in standard format (XX XXX XXX XXX)

Additional Fields (with lookup)

Field	Type	Description
found	boolean	Whether the ABN was found in the ABR
entityName	string \| null	Registered entity name
entityType	string \| null	Entity type (e.g. Australian Private Company)
abnStatus	string \| null	ABN status (Active, Cancelled)
abnStatusFrom	string \| null	Date the status became effective
acn	string \| null	Australian Company Number (if applicable)
state	string \| null	State or territory (e.g. NSW, VIC)
postcode	string \| null	Postcode of the registered address
gstRegistered	boolean	Whether the entity is registered for GST
businessNames	string[]	List of registered business names
dataSource	string \| null	`abr` when data was retrieved from the Australian Business Register

Example Response

{
  "valid": true,
  "abn": "51824753556",
  "formatted": "51 824 753 556"
}

Example Response — with lookup

{
  "valid": true,
  "abn": "51824753556",
  "formatted": "51 824 753 556",
  "found": true,
  "entityName": "COMMONWEALTH BANK OF AUSTRALIA",
  "entityType": "Australian Public Company",
  "abnStatus": "Active",
  "abnStatusFrom": "1999-11-01",
  "acn": "123456789",
  "state": "NSW",
  "postcode": "2000",
  "gstRegistered": true,
  "businessNames": [],
  "dataSource": "abr"
}

Example Response — invalid

{
  "valid": false
}