I Built a MITM Proxy to See What Claude Code Actually Sends to Anthropic

Ever wondered what Claude Code is actually sending to the Anthropic API behind the scenes? I did — so I built Claude Inspector, a macOS desktop app that intercepts and visualizes Claude Code's HTTP traffic in real time via a local MITM proxy. Claude Code CLI → Inspector (localhost:9090) → api.anthropic.com All traffic stays local. Nothing is stored or shared. How It Works Open Claude Inspector and click Start Proxy Run Claude Code with the proxy env var: ANTHROPIC_BASE_URL= http://localhost:9090 claude Every API request and response is captured and visualized in real time What I Found 1. Your CLAUDE.md is sent on every single request Every request silently prepends your project CLAUDE.md, global rules, and memory files as a system-reminder block. The structure looks like this: Available skills list (~2KB) CLAUDE.md + rules + memory (~10KB) Your actual message (whatever you typed) That's ~12KB of overhead before you type a single word — and it repeats on every request. 2. MCP tools are