GNotes is described as 'Android notepad/notebook that can synchronize with Google GMail' and is a Note-taking tool in the office & productivity category. There are more than 100 alternatives to GNotes for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Standard Notes or Google Keep. Other great apps like GNotes are Microsoft OneNote, Evernote, Simplenote and CherryTree.
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.