The task is to wire a full-featured payment gateway into my website so visitors can check out securely without being redirected. I have not settled on a provider yet—PayPal, Stripe, and Square are all on the table—so part of the work involves advising me on the best fit for fees, features, and ease of maintenance. The integration will be used only on the web version of the site; there is no mobile app to consider at this stage. Regardless of the final choice, payments must process smoothly, return accurate success and failure callbacks, and store the transaction data in my existing order database. Expect to work in a staging environment first, then push to production once every test case clears. Deliverables • Gateway of choice (PayPal, Stripe, or Square) fully implemented on the live site • Secure front-end tokenisation and server-side validation • Webhook endpoints updating order status automatically • End-to-end sandbox tests using test cards and sample orders • Step-by-step deployment and configuration guide, plus a brief hand-over call if needed Clean, well-documented code and clear instructions are a must so I can manage keys, switch providers, or extend features later on.