Read this before using free online proofreading services
Stop! Your document will thank you for it.
While we all relish things that are free, this is one case where it can do more harm than good. The only way an online proofreading service can be free is if they have figured out a way to automate the editing and grammar correction using a computer algorithm, which is a fancy word for a set of rules.
Writing cannot be accurately edited using algorithms which lack contextual awareness of your audience, intent, and tone. It’s impossible. If you want proof, read this blog post about the differences between algorithmic and human editors. Then, read this article with examples of when Microsoft Word fails to catch your errors.
When free online proofreading is a good option
If you or another human has already proofread your writing, using a free online service can serve as a great way to double-check against human error. (Funny how the opposite is not true though.)
If you are only looking for grammar check like that offered in MS Word.
If you really don’t have any money to spend for editing, then these algorithms are better than submitting your writing without any checking.
Free is worth every penny you pay.