iBill – The easiest and best Billing & Invoice Manager is an invoicing system for sole proprietors and small businesses. iBill makes it easy to manage sales, create invoices, receive and track payments, manage business accounting and calculate taxes, use comprehensive real-time reporting features to accurately measure business progress. With Online Invoices' simple (and advanced) tools, you can view business activity at any level to easily track any stage of any client, invoice, payment or employee.