Free Invoice & Estimate Maker Simple 2 go is a fast and easy invoice app for sending invoices, estimates to your customers. Free Invoice Maker Simple is the perfect invoice maker for small business owners, contractors and freelancers needing a simple and professional mobile invoice app. Create, send and track invoices on your phone and keep your finances organized. Send the invoice on the go before you leave the customer! It's extremely easy to use and saves a lot of time. The free version of