Shoptopus: Invoice Generator

Creation of a pre-made invoice template. Just select the sections you want with clicks. The content is very complete (even for French law). Very easy to use and very responsive technical support. I recommend without reservation.
When a link for sending email and an inclusion in the display of the site, at the level of the shopify customer profile, will be made, this application will be a must.
Much simpler than other applications, no code or variables or editor.