Automate invoicing with invoice ninja
Invoice Ninja is a popular open-source tool that takes care of invoicing, payments, track expenses, proposals, and time-tracking of tasks. To learn more about Invoice Ninja's history, visit this page.
Make offers a whole lot of modules and ready-made templates for Invoice Ninja. All the triggers, actions, and templates can be found on the application module documentation.
The video below covers 3 very useful integrations that help you take the work out of invoicing: