Add PayPal Gateway to Website

I need a smooth, secure PayPal payment gateway added to my website so customers can complete one-time purchases using either their credit/debit cards or their PayPal balance. Subscriptions or donation flows are not required—just straightforward checkout for product sales.

The job covers:

• Connecting the site to PayPal’s REST API (or the latest recommended SDK)
• Displaying PayPal-hosted buttons or custom-styled buttons that support the two payment methods mentioned above
• Handling success, cancellation, and error callbacks and writing clear server-side logic to confirm transactions
• Returning a clean confirmation page to the buyer and sending any necessary webhooks or order data back to my system for record-keeping
• End-to-end testing in PayPal sandbox followed by a live switch-over once everything passes

Acceptance criteria: the gateway must process real card and PayPal balance payments without errors, reflect correct totals, and log each transaction in a simple report I can review.

Please tell me which language or framework you plan to use, how long the integration should take, and any past PayPal projects you can point me to.