Grammarly

Grammarly checks grammar, spelling, and style in real-time as you write — emails, docs, social media posts. The AI suggests clarity improvements, tone adjustments, and conciseness edits. Works as a browser extension, desktop app, and in Word/Google Docs. Free tier covers basic grammar and spelling, Premium adds advanced suggestions and tone detection.

Ideal for non-native English speakers who want confidence in professional writing, anyone writing customer-facing content (support emails, marketing copy), and teams that need consistent tone across communications. The real-time feedback helps improve writing skills over time. If you write 10+ emails daily, it pays for itself in time saved.

Where it's less useful: creative writers find it overly prescriptive (it favors clarity over style), developers rarely need it, and the free tier covers most use cases for casual users. Premium ($12/month) is worth it if writing quality directly impacts your work. Otherwise, the free version + occasional ChatGPT edits work fine.