Enroute Flight Navigation is a mobile flight navigation app for Android and iOS devices. The app is free, open source, 100% non-commercial and does not collect user data.
Please have a look at the homepage.
Download the app for mobile devices on Google Play and on the App Store.
Download the app for Linux Desktop on flathub.org. Depending on your distribution, it might also be listed in your software management app.
Read the user manual.
Please have a look at the wiki pages.
There is extensive API documentation for the C++ classes.
Developers will find automatically generated experimental builds for a variety of platforms here.