Liner - Put simply, Liner is a virtual highlighter. It works on PDFs and webpages in the same way a regular highlighter works on books and magazine clippings. Read more about Liner.
Weava - Workspace to highlight, organize & collaborate on your research articles.
English Syntax Highlighter - Highlights English syntax like it's code
Quotle - Save, share & discover text from your mobile
Grammarly - Clear, effective, mistake-free writing everywhere you type.
Diigo - Diigo is a powerful research tool and a knowledge-sharing community