Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Overleaf - The online platform for scientific writing. Overleaf is free: start writing now with one click. No sign-up required. Great on your iPad.
Standard Notes - A safe place for your notes, thoughts, and life's work
TeXworks - The TeXworks project is an effort to build a simple TeX front-end program (working environment)...
Joplin - 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, tagged and modified either from the applications directly or from your own text editor.
Texmaker - Texmaker, free cross-platform latex editor