Salestrekker has an integrated ABN lookup for Australian companies.
Company clients
Search can be prompted from the 'Entity name' field (when creating a new company contact or editing an existing one) when typing in the company name or their ABN.
In Deals: Broker tools > Entity details
In Contacts: Entity edit page
Information that is returned and auto-filed into company details is: entity name, ABN (or ACN), date incorporated, date and state of registration, GST registered checkbox and date.
Employers
Search can be prompted from the 'Employer name' field (when adding a new employer for client or editing an existing one) when typing in the employer name or their ABN/ACN.
Information that is returned and auto-filed into employer details is: employer name, ABN and ANC.