GNOME Builder is fast, clean & simple IDE for GTK application development (on Linux), integrated support for Git and easy possibility to publish the application on FlatHub. This is probably the best IDE for developing applications on Linux
Geany - Lightweight IDE for Linux and Windows
HTML-Notepad - HTML WYSIWYG editor for structured documents
Visual Studio Code - Build and debug modern web and cloud applications, by Microsoft
Notepadqq - Notepadqq is a linux clone (identical application) of Notepad++
Glade - Glade is a RAD tool to enable quick & easy development of user interfaces for the GTK+ toolkit...
iNotepad - Write and organize all your texts and notes on Mac.