Secure Childcare App for Launch

Hello, I have an existing application that is mostly developed, and I’m looking for professional assistance to review, secure, and prepare it for launch. I am not looking to build a new app from scratch... (Budget: $30 - $250 USD, Jobs: Application Performance Monitoring, Backend Development, Database Administration, Mobile App Development, Security Auditing, Testing / QA, User Experience Research, User Interface / IA)