Hey Product Hunt! 👋 I built FlowLine because every AI agent I shipped followed the same story: great in the demo, then production showed up with a surprise bill, requests failing quietly, and a prompt-injection hole nobody had drawn on the whiteboard. So I built the tool I wanted before writing any code: a flight simulator for AI agents. How it works: 🗣️ Describe your agent in plain English (or speak it). FlowLine draws the whole design: models, tools, routing, caches and human approvals. 🎲 Simulate 1,500+ requests to see the cost per request, the monthly bill, latency, the success rate, and exactly which step breaks. 🛠️ Fix it in one click. Suggestions like "this judge doesn't need GPT-6" or "nothing checks this output" re-simulate instantly, and every fix can be undone with ⌘Z. 🔍 Five lenses: Structure, Replay, Context, Cost and Risk. Risk shows whether outside text (emails, web pages, uploads) can reach a risky action like a refund. 🚀 Export to LangGraph, CrewAI, the OpenAI Agents SDK, the Claude Agent SDK or n8n. It's free. Bring your own OpenAI key. It stays in your browser tab and is never stored. I'd love your help with: Designing an agent you're building (or dreaming about) and telling me if the numbers feel right Which framework or feature I should add next I'll be here all day answering every comment. Thanks for checking it out! 🙏 👉 https://flowline-psi.vercel.app/

FlowLine

Design agent systems before you build it (Figma for Agents)

Design agent systems before you build it (Figma for Agents)