Compare AI tools
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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Writesonic B | Claude Agent SDK S | Lex A | Perplexity S | |
|---|---|---|---|---|
| Tagline | SEO-first AI writer. Optimized for ranking content. | Anthropic's SDK for building your own agents on Claude. | Google Docs with an AI collaborator baked in. | AI search done right. Cited answers, not chat theater. |
| Category | Marketing | Agents | Writing | Research |
| Pricing | Free + $15-$99/mo | API usage + SDK is free | Free + $12/mo | Free + $20/mo Pro |
| Best for | Content marketers churning out SEO articles. | Developers building custom agents for their own company/product. | Essays, long-form drafts, thinking on the page. | Replacing Google for any question where you want a cited answer in seconds. |
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| Kai's verdict | B-tier. Use Claude + manual SEO thinking. Writesonic is fast but generic. | S-tier for builders. The right primitives. What Kai is built on under the hood. | A-tier. Beautiful UX. The writing app I'd pick if I only wrote long-form. | S-tier for search. I use it before Google now. If you're still Googling everything, try this for a week. |
| Link | Open → | Open → | Open → | Open → |