Grammarly

What it is

Grammarly started as a grammar checker and grew into a full AI writing assistant: real-time correction everywhere you type, plus generative AI features — rewrite for tone, shorten, adjust formality, draft replies.

What it is genuinely good at

• Everyday correctness. Grammar, spelling and punctuation fixes inline in email, docs and browsers — zero workflow change.
• Clarity. Its best feature is not grammar but concision — flagging the sentence that takes twenty words to say ten.
• Tone matching. "Sounds demanding" before your manager thinks it.

Honest limitations

It averages writing toward a corporate-safe middle — you will reject as many suggestions as you accept, and over-accepting flattens voice. Unlike a chatbot, it will not draft a strategy memo; and it can confidently "fix" deliberate style (fiction dialogue, brand voice) into beige. Free tier covers correctness; the writing-assistant features need a subscription.