PayPal Express Inline Checkout Integration

I need PayPal Express Checkout added to my e-commerce site with the Inline Checkout experience, so customers finish payment in a lightbox without ever leaving the store. The cart total, shipping, taxes and currency must pass to PayPal automatically, and once the transaction is authorised the order status on my side should flip to “paid” and trigger our usual confirmation e-mails.

You’ll connect the shop to my PayPal API credentials, wire up the JavaScript SDK, configure both sandbox and live modes, and supply any server-side hooks required for instant payment notification or webhooks. Clear setup notes and the exact code you touch or create will be part of the hand-off so I can maintain it later.

Acceptance criteria
• Inline checkout renders on cart/checkout pages and processes single-purchase payments smoothly.
• Successful, failed and cancelled payments all return accurate messages and redirect flows.
• Orders marked paid in the database match the PayPal transaction ID.
• Works on current desktop and mobile browsers.

My front-end is in place; it’s the PayPal logic I’m missing. If you’ve handled this before, especially on custom stores, I’m ready to get started right away.