Mobile app for ordering and booking

I am looking for a talented mobile developer to create a powerful and intuitive mobile app for a health company app. This will be for activating pre purchased kits and booking appointments. The app should be designed to work seamlessly on both iOS and Android devices. I have a design concept in mind which I would like the developer to implement, so no custom design will be required. Additionally, the app needs to be integrated with other systems, so the developer should have experience in leveraging other APIs in order to make sure the app is seamlessly connected to other services. This should be made in order to provide an intuitive and convenient user experience.