Invoice Machine is an online service designed to create invoices easily. It starts with a free plan and you can upgrade it to a paid one for more features.
Allows to send invoices in PDF format, set recurring invoices, integrate with Paypal or Authorize.Net. Also allows to use multiple currencies, send automatic emails, add clients, items and projects. Allows to integrate it with Basecamp project management tool.
It generates professional invoices and offers an API key to integrate with your application.
