three.dev
Verdict: Watches your AI app's live conversations through a proxy, scores each one and flags quiet failures such as a wrong refund policy or an invented discount code, with the evidence attached. Failures are grouped by cause and ranked, and your coding agent can read them over MCP to write the fix. Set up with one prompt in Claude Code, Codex or Cursor.
Fit Developer
Levels show who gets value from it — many tools work for both beginners and experts.
🚀 Getting started: Paste the setup prompt from three.dev into Claude Code, Codex or Cursor; it installs the skills and routes your LLM calls through the proxy, then check the dashboard.
✅ Good fit if you run an AI assistant or agent in production and want to know where it goes wrong.
⛔ Not for you if you don't have an AI feature with real users yet.
The score rates quality; this box tells you whether it suits you. How to read it
Free (about 50,000 requests a month, 30 days of history); Starter $79/month (6 months free launch offer); Pro $249/month; Enterprise custom · Official site: https://three.dev/ · source checked (HTTP 200)
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three.dev FAQ
Is three.dev free?
Yes, there is a free option. Pricing as we found it: Free (about 50,000 requests a month, 30 days of history); Starter $79/month (6 months free launch offer); Pro $249/month; Enterprise custom (checked 2026-11-13).
Who is three.dev best for?
three.dev is a good fit if you run an AI assistant or agent in production and want to know where it goes wrong. It is not for you if you don't have an AI feature with real users yet. Level: Developer.
What are good alternatives to three.dev?
The highest-scored alternatives in agent builders on AI Agent Ideas are Ollama (8.7/10), Zapier Agents (8.6/10), n8n (8.4/10) and OpenRouter (8.4/10).
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