My desktop-based fitness app is fully functional except for one critical piece: taking payments. I need a developer who can add seamless payment processing so users can sign up, pay with a credit or debit card, or even use cryptocurrency, and then be billed automatically for their monthly subscription. The current codebase is stable; what’s missing is the payment layer—checkout screens, secure tokenisation, recurring billing logic, and the callbacks that unlock premium content after a successful charge. I’m flexible on the card gateway (Stripe, Square, Authorize.net or another suggestion) as long as it supports subscriptions and PCI-compliant storage. For crypto, I’m open to whichever API you’ve used successfully—Coinbase Commerce, BitPay, or a lightweight alternative. Deliverables: • Fully integrated payment module handling card and crypto checkout, refunds and subscription renewals • Test environment setup plus a short walkthrough so I can run acceptance tests myself • Deployment into production with live keys, ensuring webhooks fire correctly and users gain/lose access on payment success or failure • Brief developer-facing documentation covering configuration, keys and future mobile hooks If you’ve built subscription billing on desktop apps before—ideally in the health or SaaS space—let’s talk.