We need to develop a software for hardware POS (no problem with brand).
We have a web-based software (with API) and we need to connect it a POS, to charge points on loyalty card and discarge card.
We mean POS like credit // debit card, where you stripe the magstripe (NO PC or WEB-POS).
POS will read card number and IF customer exists, permit to insert $$$ spent. IF customer doesn't exist, create customer and after permits to insert $$$ spent.
All process need to be connected via API to our software, that responds to API call in XML or JSON.
About 15 differents API call in a single process.
You must verify also brand && hardware manufacturer: you could select brand that you want for this project.