September 8, 2023 6:54 AM EDT
I think the main thing you need is open source software for creating the QR codes themselves (can do a quick Google search: e.g. http://phpqrcode.sourceforge.net/). From there you need to figure out a strategy for what features you are going to offer people. For example:
What types of codes you can create (e.g. SMS, URL, Address book)
What output you are going to provide (e.g. PNG, JPEG)
What types of codes you can create (QR, micro QR, Datamatrix)
Error correction level (e.g. 0-35%)