Payment Gateway Integration for Existing Marketplace Platform

We are looking for a developer to help with a payment integration task in an existing marketplace platform. This is a small, well-defined job, ideal for freelancers experienced with payment gateways and backend/frontend integration. The goal is to connect and validate the payment flow so users can complete transactions smoothly within the marketplace. The scope of work includes: Integrate a payment gateway into the marketplace platform. Ensure basic payment flow works correctly (create payment, confirmation, status handling). Handle simple success / error responses. Perform basic testing to confirm payments are processed correctly. This is not a full system build; the platform already exists. Requirements include: Experience with payment gateway integrations (e.g. Stripe, Mercado Pago, PayPal, etc.). Familiarity with marketplace payment flows. Ability to work with existing codebase. Clear communication and clean delivery.