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Probe Docs

Introduction

Probe is an HTTP/HTTPS debugging proxy for macOS and Windows.

It captures traffic from your computer, phones, and any device on your local network — letting you inspect, modify, replay, and automate every request and response.

The proxy core is built in Rust for high throughput; the UI is a native Flutter desktop app with a three-column layout (sidebar / traffic list / detail panel).

Who Probe is for

Section titled “Who Probe is for”
  • Mobile developers debugging an iOS or Android app’s API calls.
  • Backend & API engineers verifying request/response shape on the wire.
  • QA engineers reproducing flaky network conditions and edge cases.
  • AI / agent builders plugging Probe’s MCP server into Claude Code or Cursor for traffic-aware debugging.

What you can do

Section titled “What you can do”
  • Capture every HTTP/HTTPS request flowing through your machine or any phone configured to use Probe as its proxy.
  • See full request and response bodies — even HTTPS — by installing Probe’s CA certificate.
  • Map Local: serve a canned response without ever hitting the origin.
  • Map Remote: rewrite a URL to a different upstream (e.g. point a mobile build at staging).
  • Throttle: simulate 3G, LTE, or any custom up/down speed and latency.
  • Breakpoints: pause a request or response, edit it, and continue.
  • Compose: build a request from scratch — like Postman, but inside the proxy.
  • Script: write tiny JS programs that run on every matching request (pro.req, pro.res, crypto, assertions, environments).
  • MCP: connect an AI agent to read traffic, build requests, and run replays.

How it works

Section titled “How it works”
┌────────┐     ┌──────────┐     ┌─────────────┐
│ Your   │────▶│  Probe   │────▶│  Origin     │
│ device │ TLS │  proxy   │ TLS │  server     │
└────────┘     └──────────┘     └─────────────┘
                    │
                    ▼
              ┌──────────┐
              │  Probe   │  ← inspect, modify, replay
              │  app UI  │
              └──────────┘

When you start Probe, it:

  1. Boots the Rust proxy on a local port (default 9099).
  2. Switches your system HTTP/HTTPS proxy to point at it (macOS: networksetup; Windows: WinINET).
  3. For HTTPS, generates a per-host leaf certificate signed by Probe’s CA — your client trusts the CA once, and from then on Probe can decrypt the stream.

When you stop Probe, your system proxy settings are automatically restored.

Next steps

Section titled “Next steps”