To improve the service of my company I want to make a convenient application for clients. What companies are currently involved in development and where are the clever specialists working?

I can say that ios app development services are very popular now, for example, I recently contacted a company https://pharosproduction.com/ios-app-development-services I chose it because they make safe and functional applications. I am satisfied with the cooperation and so far there have been no problems with my app and all the clients love it very much.