Grammarly

Grammarly is the most widely used AI writing assistant, embedded in browsers, email, word processors, and desktop apps for tens of millions of people. At its core it checks grammar, spelling, and punctuation in real time, but the paid product goes further — flagging wordy sentences, inconsistent tone, hedging, and unclear phrasing, and offering one-click rewrites. Grammarly’s generative layer can also draft an email from a prompt, adjust formality, or compress a paragraph.

What keeps it ahead of built-in checkers in Word or Google Docs is reach and depth. The same engine follows you across roughly half a million sites and apps, so a Slack message, a LinkedIn post, and a client contract all get the same review. Compared with rivals like ProWritingAid (deeper for long-form fiction) or QuillBot (paraphrasing-first), Grammarly is the generalist most people reach for. The company, founded in 2009, expanded aggressively into generative AI and in 2025 acquired the email client Superhuman.

Key Features

• Real-time grammar, spelling, and punctuation correction
• Tone detector and clarity/conciseness suggestions
• Full-sentence rewrites and paraphrasing
• Generative AI drafting from short prompts
• Plagiarism detection (Premium)
• Browser extension plus native Word, Outlook, and desktop apps

Pricing

• Free: Grammar, spelling, punctuation, and a limited number of generative AI prompts
• Pro: Around $12 per month (billed annually) for tone, clarity, rewrites, and expanded AI use
• Business: Roughly $15 per user per month for team style guides, analytics, and admin controls
• Enterprise: Custom pricing with security and centralized management

Best For

Professionals, students, and non-native English speakers who write across many apps and want consistently polished output — especially anyone who values learning from the explanations behind each fix.

Limitations

Most of Grammarly’s genuinely useful help sits behind the paid tier; the free plan is closer to a good spell-checker. It can also over-correct, smoothing away deliberate voice and rhythm, so writers with a strong style should treat suggestions as optional. For deep long-form editing, ProWritingAid’s reports go further.