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Side-by-side: what they do, what they cost, what Kai actually thinks. Pass up to 4 tools via ?tools=claude,chatgpt,gemini.
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Grammarly
A
Writesonic
B
NotebookLM
S
Lex
A
TaglineGrammar check + tone + AI drafting, everywhere you type.SEO-first AI writer. Optimized for ranking content.Google's research notebook. Turns your docs into a podcast.Google Docs with an AI collaborator baked in.
CategoryWritingMarketingResearchWriting
PricingFree + $12-$15/mo Premium + team plansFree + $15-$99/moFreeFree + $12/mo
Best forNon-native English writers, business email, anyone who types a lot.Content marketers churning out SEO articles.Students, researchers, anyone with a stack of PDFs or a topic to learn.Essays, long-form drafts, thinking on the page.
Strengths
  • Works in every browser/app
  • Now has generative AI (GrammarlyGO)
  • Tone detection + suggestions
  • SEO built-in (Surfer integration)
  • Article generator for long-form
  • Chatsonic for research
  • Upload anything, ask questions, get cited answers
  • Audio Overview turns docs into a 10-min podcast
  • Great for studying
  • Clean writing UX — distraction-free
  • +++ prompt triggers AI help
  • Collaboration + AI feedback together
Weaknesses
  • Can feel naggy
  • Premium features gate basics
  • Privacy concerns (reads your writing)
  • Output quality behind Claude for polish
  • SEO automation can produce generic content
  • Google-only
  • Can be slow on large corpora
  • Less feature-rich than Google Docs
  • AI ceiling below dedicated tools
Kai's verdictA-tier for non-native English speakers. B-tier if your English is already strong — Claude does better with tone.B-tier. Use Claude + manual SEO thinking. Writesonic is fast but generic.S-tier for study. The Audio Overview is a killer feature. Try it with three of your favorite PDFs.A-tier. Beautiful UX. The writing app I'd pick if I only wrote long-form.
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