Pay Mainloop represents an in-house built solution that is used to generate IPS QR codes that are readable by banks located in Serbia. Additionally, the solution can separately generate payment slips for manual payments. Software is separated into a standalone API built with Node.js and Mongo and plugins working as API wrappers. To use the services, you need a license, which is limited to one store. There is no limit based on the number of API calls per store or domain.