Jledger is a Java Business Accounting API that consists of invoicing, general ledger, stock/inventory control, and other business APIs that will assist Java developers in building business software with ease. It will take care of the business logic like accounting double entry, Stock Balance and management (FIFO), etc., and seamlessly integrate each part of business operation as a whole.
YaBS is enterprise resource planning software that manages products and contacts as basic data, generates offers, orders, invoices, and reminders from it, and includes basic book keeping. It writes PDF or ODF (OpenOffice format) documents, and is a multiuser system. It is the successor of MP Invoicing. It can use any JDBC compliant database as a backend, and works in heterogenous networks, allowing fine grained security settings. It can also be extended with modules.