Grammarly is a free proofreading web application that finds and explains in-depth grammar, spelling, and punctuation mistakes online. Grammarly works anywhere you write online, including Twitter, Facebook, email and more. There is also a Google Chrome plugin that proofreads everything from your blog posts to tweets instantly. The Safari and Firefox versions will release later this year too. They also now have a plug-in for Microsoft Office. It checks for over 250 grammar mistakes, including contextual spelling errors, vocabulary misuse and more. It doesn't just high light the error, but gives you an explanation of why it tagged it as a mistake and how to fix it.
This is great for writers and students as it helps them find mistakes before publishing and helps them learn from these mistakes so they don't make them again and learn the proper grammar.
I've been using it for the last couple of weeks and it has caught some mistakes that I missed. It's easy to use and very helpful as a learning tool.
Grammarly works with: