Experienced Full-Stack Developer Needed for React Native Backend Debugging & API Optimization

We are looking for an experienced full-stack developer with strong expertise in React Native and backend development to help identify, troubleshoot, and resolve several issues in our production mobile application. The application is already live, but users are experiencing intermittent problems related to API communication, authentication, and data synchronization. The ideal candidate should be comfortable analyzing both the React Native frontend and the backend services to determine the root cause of bugs rather than simply applying temporary fixes. Your responsibilities will include reviewing the existing codebase, debugging REST API requests and responses, identifying issues related to authentication (JWT/OAuth), investigating server-side errors, optimizing database queries where necessary, fixing inconsistent data returned by the APIs, and ensuring proper error handling throughout the application. You will also be expected to diagnose performance bottlenecks, improve response times, resolve crash reports, and ensure seamless communication between the mobile client and backend services. Experience with Node.js, Express.js or NestJS, PostgreSQL or MongoDB, Firebase, Git, and API testing tools such as Postman is highly desirable. In addition to resolving the current issues, we expect clean, maintainable code that follows industry best practices. Please document the problems you identify, explain the solutions implemented, and provide recommendations for preventing similar issues in the future. Strong debugging skills, attention to detail, and excellent communication are essential. This project may lead to long-term collaboration for future feature development, maintenance, and application enhancements if the initial engagement is successful.