CliqTags has a built-in QR Code generator for CliqTags sites, so nothing extra is needed for that. You’ll find that feature under Access per site, and the QR Code is automatically generated for accessing that specific site.
Abiro QR Code Generator
For more general use, as well as e.g. addressing specific pages on CliqTags sites, you can use Abiro QR Code Generator. You can also generate self-contained QR Codes via this tool, e.g. for contact info.
Canva QR Code Generator
If you use Canva for banners and such there’s an integrated QR Code Generator where QR Codes are easily added to content you create.