QR-Einzahlschein / QR-Rechnung (Schweiz)
Work in progress not yet ready for production!
GPL / Proprietary (contact me, see source header)
Specifications are available for download at:
https://www.paymentstandards.ch/
FPDF is a Free PHP PDF Library.
Source of the Liberation Fonts, which are officially allowed, can be embedded and therefore are displayed equals on all devices, and are available for free.