Grammarly

Grammarly is the default grammar checker for most writers thanks to its ubiquitous browser extension and instant real-time underlining in Gmail, Google Docs, WordPress, and almost everywhere else. It excels at mechanical errors but is built for business and academic writing, not fiction.

• Best for: Catching typos, comma splices, and subject-verb errors as a final pass — not as a fiction author's primary self-editor
• Key features: Real-time corrections everywhere, tone detector, full-sentence rewrites, plagiarism check (Pro), Grammarly Go AI prompts (100/mo on free)
• Pricing: Free tier (basic + 100 AI prompts/mo); Pro $12/mo billed annually ($144/yr) or $30/mo monthly
• Limitations for fiction: Flags intentional fragments, "And/But" sentence starts, and stylistic repetition; no manuscript-level reports; 50,000-word daily limit; community consensus is it "flattens author voice"
• Privacy note: Training data is on by default for Free/Pro individual accounts — opt out manually in Privacy settings if you don't want your prose used to improve models