Grammarly is a valuable online editing tool that can find errors you may have missed when proofreading your writing. The program has both free and premium versions.
The free version picks up on basic spelling and grammar errors more accurately than the majority of other programs. For some students, the free account will suffice and is certainly a good starting point for anyone. The premium program has a monthly fee because it is more robust. The writer gets customized checks for different document types, vocabulary suggestions, and other extras.
As with other online tools, not all suggestions are correct, but the writer does not have to accept every edit. The suggested edits come with a basic explanation and a more in-depth explanation (a valuable tool for strengthening writing skills). There are video reviews on YouTube that allow you to see what Grammarly is all about.
Regardless of which version you use, Grammarly sends a monthly email with your writing statistics (types of errors most frequently made, etc.). Once you create an account, Grammarly will start sending emails with special offers, so perhaps start with the free account and see if a good upgrade offer comes your way.