Omnichannel POS Gateway Setup

I’m rolling out a new point-of-sale system that must handle both in-store swipes/taps and online checkout from the same payment backbone. The first milestone is to recommend the most cost-effective gateway... (Budget: $30 - $250 USD, Jobs: API Development, JavaScript, Payment Gateway Integration, Payment Processing, PCI Compliance, PHP, POS development, Python, Software Development, Technical Documentation)