First, you should know the main types of healthcare apps that exist. It will help you make the right decision on choosing the category that is necessary for your field of activity. It is worth noting that there are more existing types, but I will consider the most popular ones you may choose for custom healthcare app development.
Waoo its really good idea, If you are thinking about creating a healthcare application you could start from an app for telemedicine/telehealth, HIPAA, EHR/EMR. Nowadays for Covid-19 pandemic such kinds of applications are becoming popular and profitable.
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