Invoice Falcon

The app does everything you will need and more. The basic features get your invoicing up and running quickly , with VAT details etc which is need in the UK. Beyond that there are loads of other features for people with high volume orders and invoicing needs. Support is excellent and responsive Same day :) Will be using on my other new shopify sites coming soon

Invoice Falcon is a powerful and customisable invoice generation app which helps us ensure all our invoices are perfect before sending to our customers. This app has a great edit function, which allows you to modify the generated PDF - you can click and edit text in any box, change information that was imported from customer account and order, and modify this information if required before sending or exporting as pdf. It allows for customisation and design of your invoice template by enabling or disabling different fields, and customising the colours according to your brand. It makes it easy for non-technical orders to update, modify and create invoice templates. Invoice Falcon is a great fully featured invoice app for Shopify.

We have been using the app for our business and it has been the perfect find.
The settings are easy to understand and the invoices look perfect. It is very easy to download the invoice of the orders integrated with shopify. You don't need to enter any detail of the order.
The support team is also very helpful.
As we have just started out, we can't afford to pay every app, this is the best free invoice app providing 50 free invoices. As the business grows, we won't mind paying for this one!