Grammarly is an automated grammar tutor and revision support tool that helps you to improve your writing skills and corrects your grammar.
You can check their ESNcard page at https://esncard.org/grammarly
You can check their website at https://www.grammarly.com/
ESNcard holders can have a 50% discount for the annual Premium account.
They just need to use the link: https://www.grammarly.com/upgrade