I have an in-house flight-ticket and restaurant-table booking platform already running on HTML, CSS, JavaScript, PHP, and MySQL. What it now lacks are two critical upgrades: a robust user-authentication flow and a fully functional payment gateway. The authentication layer must cover classic email-and-password registration/login as well as an optional two-factor step (OTP or similar). Users should be able to create accounts, log in, reset passwords, and see a friendly prompt for the second factor whenever it is enabled. Sessions need to stay secure without breaking the existing booking flow. On the payment side, I want a seamless gateway integration so customers can pay for flights or table reservations without leaving the site. I am open to popular providers—Stripe, Razorpay, PayPal, etc.—as long as transactions, callbacks, and error handling are rock-solid and receipts automatically record to MySQL alongside the existing booking data. Deliverables • Clean, well-commented PHP/JavaScript code that drops into my current project structure • Database migrations or scripts to support user tables, 2FA tokens, and payment records • Any front-end components or modals needed for login, 2FA verification, and checkout • Brief setup documentation and a quick test plan so I can verify flows end-to-end Acceptance criteria 1. A brand-new user can register with email/password, be prompted for 2FA (if activated), and see their booking dashboard. 2. An existing user can complete a flight or table booking and pay successfully; the booking status updates automatically. 3. Failed logins, expired 2FA codes, and declined payments show clear, user-friendly messages while logging technical details server-side for review. The codebase is simple and I’m available to answer architecture questions quickly. Looking forward to seeing how you can elevate the project’s security and revenue flow.