I run a service-based website that already processes card payments, but I now want to add crypto support through the official NowPayments API. The sole purpose of this integration is to let customers pay one-time invoices for my services; I do not need recurring billing or donation flows. What I have now • A live production site with existing checkout logic • API keys from my NowPayments account • Access to the codebase and server (SSH / cPanel / Git, whichever you prefer) • Clear success / error pages and UI placeholders ready for the new option What I need from you 1. Implement the NowPayments payment endpoint to create invoices in real time based on an order’s total. 2. Handle IPN/webhook callbacks so paid orders are automatically marked as “paid” in my database. 3. Display the NowPayments-generated payment URL or embedded widget to the customer. 4. Add graceful error handling and fallback messaging. 5. Provide brief, commented code plus a short read-me so I can maintain the integration later. Acceptance criteria • A test order completes end-to-end with cryptocurrency and updates order status correctly. • Webhook verification follows NowPayments security guidelines. • No existing payment methods are disrupted. • All new code is committed via a clean pull request or delivered as a patch file. If you have hands-on experience with NowPayments (or similar APIs such as Coinbase Commerce, BitPay, etc.) and can turn this around quickly, let’s talk. Please mention the language or framework you’d like to use so I can grant access to the right repository branch.