FeProxy

FeProxy is a proxy tool use for web development like the Fiddler, and we use Chrome Devtools to inpect net traffic.

Install

[sudo] npm install feproxy -g

Usage

feproxy

It prints the two addresses you need:

👉 Proxy server http://192.168.1.5:8888
🚀 Inspect page http://192.168.1.5:8888/admin.html

1. Point your browser / phone / emulator at the proxy server (host + port, HTTP proxy).
2. Open the inspect page to watch traffic in Chrome DevTools' network panel and to edit forwarding rules.

To capture HTTPS, install FeProxy's root certificate on the client and trust it — open http://<host>:<port>/feproxy.crt on the device (the cert also lives in ~/.feproxy, named feproxy-<user>.crt). Without it HTTPS still works, but only as an opaque tunnel.

Options

feproxy [options]

Option	Default	Description
-p, --port	8888	Service port
--hostname	feproxy.org	Hostname of feproxy self site
-c, --config	~/.feproxy	Directory of config files
--https / --no-https	true	Decrypt (MITM) https requests so they can be captured and modified
--ignore-cert-error	false	Ignore upstream certificate errors
--inspect / --no-inspect	true	Push requests to devtools; --no-inspect forwards only
--auth / --no-auth	false	Enable proxy basic authentication
--username	feproxy	Username of proxy basic authentication
--password	feproxy	Password of proxy basic authentication
-v, --version		Output the version number
--help		Show help

feproxy -p 8080                              # start on port 8080
feproxy --no-https                           # do not decrypt https requests
feproxy --no-inspect                         # forward only, no capturing
feproxy --auth --username me --password pwd   # require proxy credentials

Authentication applies to proxied traffic only — the inspect page, /feproxy.crt and the other feproxy endpoints stay open. Credentials cannot be changed from the inspect page.

Rules

Rules live in projects, editable on the inspect page (settings button, bottom right) or in ~/.feproxy/config.json. Each rule matches match (a case-insensitive regexp) against the full request URL and applies one action, written in the UI as a single to string:

to	Effect
http://127.0.0.1:3000/$1	Forward the request to another URL
host://127.0.0.1:3000	Keep the URL, send it to this host/port
file:///path/to/dist/$1	Serve a local file
status://404	Reply with a status code (status://302?location=... to redirect)
delay://1000	Delay the request by N ms
header://?cache-control=no-cache	Override response headers

$1, $2… are back-references to the capture groups of match. Rules of different types stack (delay + header + a terminal http/file/status); for the same type only the first match wins.

On the wire (and in config.json) a rule is { enable, match, type, param }:

{
  "projects": [
    {
      "name": "my-app",
      "enable": true,
      "rules": [
        { "enable": true, "match": "^https?://example\\.com/static/(.*)", "type": "file", "param": { "path": "/Users/me/app/dist/$1" } },
        { "enable": true, "match": "^https?://example\\.com/api/", "type": "delay", "param": { "delay": 1000 } }
      ]
    }
  ],
  "https": true,
  "ignoreCertError": false,
  "inspect": true
}

config.json is also where https / ignoreCertError / inspect are persisted when you toggle them on the inspect page. Precedence is defaults ← config.json ← CLI options.

Development

git clone https://github.com/feix760/feproxy.git
cd feproxy
npm run dev