Mobile App Bug Fixing

I need an experienced software developer to fix bugs on my mobile application available on both iOS and Android platforms.

The application currently has several critical issues:
- Database issues
- Crashes frequently
- Performance issues
- UI/UX problems

Ideal Skills and Experience:
- Proficiency in mobile app development for both iOS and Android
- Strong problem-solving skills to diagnose and fix crashes
- Experience in optimizing app performance
- UI/UX design knowledge to enhance user experience
- Familiarity with debugging tools and methodologies

Please provide a portfolio with relevant experience.