MonoDevelop is a free and open-source IDE for Mono/.NET. It has support for C# and F# programming languages, with releases 4.x-5.x also including support for C/C++ projects. It is built using the Gtk# toolkit, is written in C# and is in the official repositories of Fedora.
To install MonoDevelop using DNF run:
sudo dnf install monodevelop
To install it using Flatpak (which will provide a more up-to-date version of MonoDevelop) first install Flatpak with:
sudo dnf install flatpak
flatpak remote-add --user --from gnome https://sdk.gnome.org/gnome.flatpakrepo flatpak install --user --from https://download.mono-project.com/repo/monodevelop.flatpakref
and then one can start MonoDevelop by running:
flatpak run com.xamarin.MonoDevelop