PHP/MySQL : Payment Integration (Stripe & PayPal) and User Authentication for Custom E-Commerce Site

PHP/MySQL Developer: Payment Integration (Stripe & PayPal) and User Authentication for Custom E-Commerce Site Project Description: We are looking for an experienced PHP backend developer to enhance our custom-built e-commerce platform. The shop is a proprietary development based on Plain PHP and MySQL. We need a clean, secure, and efficient implementation of payment gateways and user-related features. Scope of Work: Payment Integration: Stripe: Implement Stripe Checkout (hosted page) for credit card and local payment methods. PayPal: Integrate PayPal Checkout using the latest REST API/SDK. Webhooks: Set up robust webhook handling for both providers to ensure order status updates (e.g., payment_success) are processed even if the user closes the browser. User Authentication & Security: Build a secure Login/Registration system. Implement password hashing using password_hash() (Argon2 or Bcrypt). Ensure protection against SQL injections (mandatory use of PDO or MySQLi with Prepared Statements). Customer Dashboard: Create a "My Account" area where users can see their profile. Display a "Recent Orders" list by querying our existing orders and users tables. Technical Requirements: Strong PHP 8.x skills (Object-Oriented Programming preferred). MySQL expert: Ability to work with existing database structures and write efficient JOIN queries. API Experience: Proven track record of integrating Stripe and PayPal SDKs via Composer. Security First: Knowledge of CSRF protection, session management, and environment variables (.env) for API keys. Deliverables: Clean, well-documented PHP code. Database migration/update scripts (if schema changes are needed). Brief documentation on how to configure the API credentials. How to Apply: Please start your application with the word "Backend" so I know you’ve read the full description. Briefly describe your experience with custom PHP shops (not CMS-based) and mention which Stripe/PayPal integration methods you prefer.