Invoice Master is described as 'Intuitive invoicing software designed for freelancers and small businesses to streamline billing and improve cash flow' and is a Invoicing software in the business & commerce category. There are more than 50 alternatives to Invoice Master, not only websites but also apps for a variety of platforms, including Windows, Mac, iPhone and iPad apps. The best Invoice Master alternative is Frappe Books, which is both free and Open Source. Other great sites and apps similar to Invoice Master are Invoice Ninja, Manager, Skrooge and Akaunting.