Some free grammar checkers include Grammarly.com and GingerSoftware.com. Both of these websites offer a more detailed grammar checker for a small monthly fee and registration.
On Grammarly.com, writers upload a section of text into the grammar checker. The free grammar checker looks for 250 common grammar errors, word choice and instances of plagiarism. The system also offers word choice enhancement. Writers can create an account and download an add-on to their Internet browser for free.
At GingerSoftware.com, writers copy and paste a sentence to get the grammar checked. This system looks for common errors, such as subject verb agreement, consecutive nouns, singular / plural nouns and other items.