[lloydatkinson]

If you're OK with paying ~£0.05 per PDF you can just use Adobe's PDF API where you supply a word document with {{ name }} like variables in it and a JSON file and you get back a PDF with it all filled in. This way you just change the styling and layout with a word editor.

[Rafsark]

Yep, that’s a solution. But editing millions of invoices would cost way to much I guess. Depending on your company size and what you want to achieve though

[AnhTho_FR]

Yep I should have added it as well in my prev answer, and doing it for a reasonable cost at scale is not trivial!