Making iOS and Android App in one free Development Environment [duplicate]

This question already has an answer here:

• iOS / Android cross platform development [closed] 9 answers

I am searching for a development environment for making Android and iOS devices. Before, I made a website for my private project (something like Siri), but I had some problems with the impressum and so I am looking for a development tool. I have also seen PhoneGap, but I do not have good experiences with this tool and Android Studio is just for Android. Furthermore there are a lot of App Builders in the web but most of them aren't free and I want to code by myself too.

I hope someone can help me, thanks.