ABN Lookup API: search an Australian company by ABN, ACN or GST number

One REST call turns an ABN, an ACN or a company name into the registered company: legal name, type, status, state and postcode, and the GST number where there is one. A key from the dashboard is the whole setup.

The short answer

Call GET /companies/search?country=AU&abn=49004028077 with a bearer key and you get the company behind that ABN as JSON. The same endpoint takes the ACN (company_number=004028077, bare digits or the 3-3-3 form), the GST number (vat=, which is the bare ABN) and a partial name for a type-ahead field. The ABN is checked first: one that fails its check digit is a 400 validation_error before any lookup, so a typo costs nothing.

That is Prometiam reading ASIC's Company Dataset and the ABR's ABN Bulk Extract, joined on the ACN. It is a different route from the ABR's own web services, which are free but need you to register for a GUID and then build against their schema. If you already hold a GUID and only ever look up one ABN at a time, the ABR is enough. If you want one key, one response shape for 27 countries, name search and batch calls, this is the shorter path.

Four ways in, one record

You have	Parameter	What happens
An ABN (11 digits)	abn=	Checked with the ABR algorithm, then matched to a company that has that ABN.
An ACN or ARBN (9 digits)	company_number=	Bare digits, 004 028 077 or an ACN prefix all work; the check digit is enforced.
A GST number	vat=	The bare ABN. Only companies whose ABN is active and registered for GST are found.
A name or part of one	name=	Normalised partial match ranked by score, built for autocomplete.

Each match returns the same object as every other country: company_name, company_number (the ACN in 3-3-3 form), abn, legal_form (APTY, APUB or FNOS) with the class, status and the register's own status_code, region (the state) and postal_code, previous_names, and vat_number with vat_number_source set to register. Pass the returned id to GET /companies/{id} for the detail.

Validate before you call

The ABN check is public: subtract 1 from the first digit, multiply the eleven digits by the weights 10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, add the products and the sum must divide by 89 (the ABR documents it on its ABN format page). Our ABN checker runs it in the browser. A number that passes is well-formed, not proof that the business exists or is current; that is the register match.

Batch and monitoring

POST /companies/lookup takes up to 100 items, each ACN or ABN counted as one request, which suits cleaning a supplier list or a CRM export. To be told when something changes, POST /monitor with the company id sends a webhook on a status change, a deregistration or a register-change event (name, status, legal form, registered address), dated by the weekly read that first shows the change, none before the first load in October 2026.

What you do not get

• A street address. The register data carries the state and the postcode only; the street and city fields are null.
• ABN or GST history. vat= finds a company while its ABN is active and registered for GST, as of the last weekly read. The dates the registration started or stopped are what ABN Lookup shows; we do not replace it.
• Sole traders, trusts, partnerships, associations and cooperatives. An ABN that belongs to one of them returns nothing even though it exists.
• Officers, share capital, an activity code or insolvency notices. Not part of the Australian record, and there is no in_liquidation status: external administration shows as in_administration.

Australia is included in every plan at no upcharge. The 14-day free trial includes 500 credits, needs a card and charges nothing; Starter (EUR 9.99 a month, 1,000 credits) follows unless you cancel. A company record costs 1 credit; an error response costs nothing. See pricing for the plans.

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Contains data from the Australian Securities and Investments Commission (ASIC) Company Dataset and the Australian Business Register (ABN Bulk Extract), licensed CC BY 3.0 AU (creativecommons.org/licenses/by/3.0/au/). Adapted by Prometiam (joined, normalised, status derived).