Ghostnote is described as 'adds contextual notes to almost anything on your mac. Add notes & todos to folders, applications, open documents, even websites. Think about it as post-it-notes for your OS' and is an app in the Office & Productivity category. There are more than 100 alternatives to Ghostnote for a variety of platforms, including Windows, Mac, Online / Web-based, Android and iPhone. The best alternative is Joplin, which is both free and Open Source. Other great apps like Ghostnote are Standard Notes (Freemium, Open Source), Google Keep (Free), Microsoft OneNote (Freemium) and Evernote (Freemium).
Noti is tool allowing you to easily receive notifications from web applications directly on your desktop. No need to keep a web page open, just run our little app on your computer and you’ll be able to start receiving notifications from supported web applications.
scrible lets you highlight and annotate web pages and easily save, share and collaborate on your web research with others. Smarter Web reading & research. Annotate, bookmark, save, manage & share online articles.
Jarnal is an open-source application for notetaking, sketching, keeping a journal, making a presentation, annotating a document - including pdf - or collaborating using a stylus, mouse or keyboard. It is similar to Microsoft .
Osmo is a handy personal organizer, which includes calendar, tasks manager, address book and notes modules. It was designed to be a small, easy to use and good looking PIM tool to help to manage personal information.