Xero develops cloud-based accounting software for small and medium-sized businesses. The key features of Xero include automatic bank and credit card account feeds, invoicing, accounts payable, expense claims, fixed asset depreciation, purchase orders, and standard business and management reporting. It offers a free API that enables customers and 3rd-party software vendors to integrate external applications with Xero. It also incorporates a payroll feature for users in the Australian and United States markets. All financial data is stored in the cloud on a single unified ledger, allowing users to work in the same set of books regardless of location or operating system.