Glosbe - Huge collaborative massively multilingual dictionary.
LanguageTool - Free proofreading tool for OpenOffice, LibreOffice, Firefox, and Chrome.
Visuwords - The fun and free way to look up definitions. THE graphical dictionary and visual thesaurus.
Grammarly - Clear, effective, mistake-free writing everywhere you type.
DocTranslator - Instantly translate and keep the formatting of any document in any language. Free!
Gramlee.com - Online grammar check, proofreading and copy editing services.