Integrate Razer Payment Gateway

I need a developer who knows Razer’s merchant APIs inside-out to plug the gateway into my project and hand it back fully functional. The site/app isn’t locked to any one platform yet, so please be comfortable working with common stacks such as PHP + MySQL, Node, or a modern framework like Laravel, React, or Flutter if it ends up being mobile.

Here’s what I expect:
• A seamless checkout flow that accepts cards, Razer Gold/Pay, and any other methods the gateway supports in my region.
• Clear handling of success, failure, and callback notifications so orders update automatically.
• A short sandbox demo so I can run end-to-end tests before we flip the switch to live mode.
• Clean, well-commented code and a quick hand-over note explaining where keys, webhooks, and environment variables sit.

If you have prior launches with Razer or similar gateways (Stripe, PayPal, etc.), point me to them—speed and reliability are my top priorities.