Audit Existing Web App and Add Secure Payment Feature

About the Project We have an existing web application that is already live in some form, but it needs a technical review before we add a payment feature. The immediate goal is to understand the current codebase, identify any security or UX issues, and then implement a reliable payments flow. If the first phase goes well, there may be ongoing support and development work. What We Need First I’m looking for a developer who can review the current web app and provide a practical audit, not just a high-level opinion. The audit should cover: - Code quality and structure - User authentication and account security - Existing backend/API setup - Frontend issues affecting user experience - Any obvious bugs, performance issues, or scalability concerns - Recommendations before adding payments Payment Feature After the audit, we want to add a secure payment flow. The exact payment provider can be discussed, but Stripe is likely preferred. The feature may include checkout, payment status handling, error states, confirmation screens, and backend validation through secure API integration. Technical Context The app uses web technologies and may involve JavaScript on the frontend and Python on the backend. I need someone comfortable working with an existing codebase, reviewing REST APIs, improving authentication flows, and making UI/UX adjustments where needed. Deliverables - Initial technical audit with clear findings - Recommended plan for payment implementation - Secure payment integration - Testing of payment and user flows - Documentation of changes made - Suggestions for ongoing maintenance and support To Apply Please include: - Examples of web apps you have worked on - Your experience with JavaScript, Python, and API development - Any Stripe or payment integration experience - What you would review first in an existing app takeover - Your availability and whether you can provide ongoing support Please start your reply with the word AUDIT so I know you read the full post.