Fixes & Improvements for Existing Android & iOS Apps

I need an experienced Android and iOS App Developer to fix and improve my existing mobile application. The app is already developed, but it requires technical fixes, performance improvements, UI adjustments, and feature enhancements. The ideal developer should be able to review the existing codebase, identify the root causes of issues, and implement reliable fixes without affecting existing functionality. Requirements: Fix existing bugs, crashes, and errors Improve app performance and stability Fix UI/UX and responsiveness issues Resolve API, Firebase, and third-party integration issues Improve or modify existing features Test fixes across Android and iOS devices Provide clean, maintainable code Experience with Swift, Kotlin, Flutter, Firebase, APIs, and mobile app deployment is preferred.