Cross-Platform Productivity Mobile App Development

I'm looking for an experienced app developer to create a mobile productivity app. The app will need to be compatible with both iOS and Android platforms.

Key Requirements:
- Proficiency in cross-platform mobile app development
- Prior experience in developing productivity apps
- Knowledge of iOS and Android platform guidelines
- Strong UI/UX design skills to create an intuitive user interface
- Ability to integrate features like task management, reminders, and note-taking

Ideal Skills:
- Expertise in Flutter, React Native or similar technologies
- Strong back-end development skills for server integration
- Experience in implementing in-app purchases and subscriptions
- Knowledge of data security and user privacy standards

I am looking for a freelancer who can deliver a high-quality, user-friendly app within the agreed timeline. Please provide examples of your previous work in your proposal.

The app should have a colorful and vibrant design theme.