multibro

A Node.js CLI for multi-browser proxy management — spin up any number of persistent, WebRTC-leak-proof Chromium profiles, each routed through its own automatically-sourced and health-checked proxy, with one command. Built on Playwright.

"bro" is short for browser; "bros" is simply more than one. It's silly. It's also exactly what you type fifty times a day if you do this for a living.

npx multibro 1-10 --country=DE

Ten Chromium windows. Ten different German exit IPs. Zero manual proxy shopping. That's the whole pitch.

Why multibro exists

Anyone running more than one browser profile at a time — for scraping, QA, ad verification, marketplace accounts, affiliate testing — eventually builds the same janky pile of scripts: a config file mapping profiles to proxies, a health-checker that pings each proxy before use, some duct tape around WebRTC so the "proxied" browser doesn't just leak your real IP anyway, and a manual routine for sourcing new proxies when old ones die (they always die).

multibro is that pile of scripts, already written, with the duct tape replaced by something sturdier.

What it's good for

• Web scraping & data collection — rotate exit IPs per profile without hand-managing a proxy pool
• Multi-accounting — marketplaces, social platforms, ad accounts, each in its own isolated, persistently-logged-in profile
• Geo-testing & localisation QA — check what a page, price or ad actually looks like from a given country
• Ad verification & affiliate/CPA testing — see the creative, landing page or redirect chain a real visitor in that country would see
• SEO rank tracking across regions — query search results as they appear from different countries
• Browser automation at scale — a scriptable base for anything built on Playwright that needs many concurrent, distinct identities

See it work

npx multibro 1,2,4-6,7                       # open bros 1,2,4,5,6,7 (creating any that don't exist yet)
npx multibro 1-5 https://ifconfig.me         # ...and load a URL in each, to eyeball the exit IPs
npx multibro 1-5 --country=US --protocol=ANY # restrict sourcing to US proxies, any protocol

Run it. Watch five real Chromium windows open, each quietly proving it's coming from somewhere else.

Installation

git clone [email protected]:vvmspace/multibro.git
cd multibro
npm install          # also builds the TypeScript sources (see `npm run build`)
npx playwright install chromium

Requires Node.js 18+.

Usage

npx multibro [list] [url] [--country=DE | -c DE] [--protocol=http | -p http]

| Argument | Meaning | | --- | --- | | list | Bro ids to open, e.g. 1,2,4-6,7. Omit it to open every bro already in bros.json. Any id not yet in the ledger is created on the spot. | | url | A page to load in each browser. Optional. | | --country, -c | ISO country code to restrict proxy sourcing to. Defaults to whatever bros.json specifies, or ANY. | | --protocol, -p | Proxy protocol to restrict sourcing to (http, socks4, socks5). Defaults to http; pass ANY to disable filtering. |

Configuration: bros.json

Created and maintained automatically, but entirely hand-editable should the fancy take you:

{
  "bros": [
    {
      "id": 1,
      "country": "DE",        // optional; overrides the global country for this bro
      "user_dir": "bro1",     // optional; defaults to `bro${id}`
      "proxy": {
        "proxy": "socks5://69.61.200.104:36181",
        "protocol": "socks5",
        "ip": "69.61.200.104",
        "port": 36181,
        "https": false,
        "anonymity": "transparent",
        "score": 1,
        "geolocation": { "country": "ZZ", "city": "Unknown" }
      }
    }
  ],
  "home_dir": "tmp",   // optional; base directory for relative user_dirs and bros.json itself
  "country": "ANY",    // optional global country filter
  "protocol": "ANY"    // optional global protocol filter
}

home_dir and profile locations

If HOME_DIR is set in .env, or home_dir is set in bros.json, a relative user_dir resolves to ${home_dir}/${user_dir}; otherwise it resolves relative to wherever you happen to be running the command. The same rule governs where bros.json itself lives: ${HOME_DIR}/bros.json if HOME_DIR is set, ./bros.json otherwise.

Copy .env.example to .env to set HOME_DIR:

cp .env.example .env

How proxy sourcing actually works

No paid proxy subscription required to get started: when a bro needs a proxy, multibro pulls the proxifly free proxy list and checks candidates five at a time, with a generous timeout per attempt, until it has gathered SPEED_MULTIPLIER × (proxies still needed) working candidates of the right protocol and country — or exhausts the list, whichever comes first. The fastest survivors are assigned; the rest are left for another day.

Country matching is applied twice, for the avoidance of doubt: once cheaply against the list's own (occasionally optimistic) geolocation field, and once for real, by routing a request through the candidate proxy and asking ipwho.is where it actually emerged. A proxy claiming to be German that turns out to surface in the Netherlands is shown the door — free proxy lists lie about this more often than you'd like.

Should the automatic search come up short, multibro asks, one bro at a time, which country to try next — press Enter for "any will do".

Naturally, nothing stops you plugging in your own paid/residential proxies by hand-editing bros.json — multibro will happily health-check and reuse whatever's already there before it goes shopping for more.

Privacy: no WebRTC leaks

Every browser launches with WebRTC comprehensively disabled — no RTCPeerConnection, no getUserMedia, no STUN candidates sneaking your real IP address out from behind the proxy. Chromium is also flagged to route any WebRTC traffic that somehow survives exclusively through the proxied connection. A proxy that leaks your real IP through WebRTC isn't a proxy, it's a liability — multibro treats that as a bug worth closing, not a footnote.

Window size is randomised to between 85% and 95% of the smaller of your actual screen and a 13" MacBook Air's resolution, so as not to advertise itself with suspiciously round numbers.

Project layout

index.ts             entry point
src/
  libs/
    cli.ts            argv parsing
    config.ts          bros.json + user_dir resolution
    proxy.ts            proxy checking and sourcing
    browser.ts           Chromium launch, WebRTC lockdown, window sizing
    screen.ts             primary screen resolution detection
    types.ts               shared types
dist/                 compiled output (npm run build)
tmp/                  default home_dir (browser profiles, bros.json)

Written in strict TypeScript. npm run build compiles; npm run dev runs straight off the .ts sources via tsx; npm run typecheck checks types without emitting.

Contributing

Issues and pull requests welcome at github.com/vvmspace/multibro. If you've got a proxy source, a detection vector, or a use case multibro doesn't cover yet, that's exactly the sort of thing worth opening a ticket about.