Grammarly

Grammarly is the most complete writing assistant, and the one most people picture when they say grammar checker. It checks spelling and grammar, suggests tone and clarity changes, and includes AI features for drafting and rewriting. It works on Chrome, Firefox and Edge, and on Safari through a Mac app.

The company renamed itself Superhuman in October 2025, and the legal entity in the current privacy policy is Superhuman Platform Inc., but the product is still called Grammarly. The extension runs your text through Grammarly's servers and asks to read and change data on all websites, which is how it works in any text field.

Open the privacy settings on day one. Grammarly's support page says the Product Improvement and Training setting is on by default for free, Premium and single-user Pro accounts, which lets it use your content to train its models. You can switch it off at account.grammarly.com/security/privacy. The privacy policy, effective 6 July 2026, says it does not sell user content and earns money from paid plans, but that identifiers and browsing data are shared with advertising partners. Ratings are mixed, at 3.9 on Chrome and Edge. It is polished and widely used, but also the pick that asks for the most trust.