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phantomas npm Inline docs code style: prettier Coverage Status CodeFactor

Headless Chromium-based modular web performance metrics collector. And why phantomas? Well, because :)



Via npm


npm install phantomas

This will install a recent version of Chromium supported by puppeteer module.

Via Docker

You can use phantomas Docker image:

docker pull macbre/phantomas:latest

Or you can fetch from GitHub's Containers registry

docker pull



You can get support for phantomas via xs:code.

Usage example

const phantomas = require('phantomas'),
    promise = phantomas('');

    then(results => {
        console.log('Metrics', results.getMetrics());
        console.log('Offenders', results.getAllOffenders());
    catch(res => {

// events handling
promise.on('recv', response => {
    console.log('Response: %s %s [%s]', response.method, response.url, response.contentType);

// including the custom one emitted by phantomas modules
promise.on('domQuery', (type, query) => {
        console.log('DOM query by %s - "%s"', type, query);

Or run ./examples/index.js.

Development version

To get the latest development version of phantomas (and install all required dependencies):

git clone
npm install

Running tests

First you need to start a local nginx container that will serve static assets used by integration tests suite. Then simply run npm t:

npm t

All pull requests that are filed for this repository will have tests run via GitHub Actions.

Having problems?

Please refer to /


  • modular approach - each metric is generated by a separate "module"
  • phantomas "core" acts as an events emitter that each module can hook into
  • in-depth metrics such as: number of events bound via jQuery, calls to window.writeor complex and duplicated CSS selectors (via analyze-css)
  • JSON as an output format
  • easy integration with other nodejs projects via CommonJS module (see API docs)
  • metrics can be emitted from JavaScript code of the page phantomas is run against (thanks to helper functions available in window.__phantomas)
  • device profiles allow phantomas to emulate mobile or tablet (by setting a proper user agent and viewport)


All the contributors


phantomas comes as a CommonJS module (see API docs) that you can use in your nodejs projects.

You can also use it as a command line tool. Run phantomas -h for more details.


Please refer to /docs/ file for a full, up-to-date list of all available modules and metrics that phantomas emits.

For developers

Let's make Web a bit faster!



Introductions to phantomas and use cases:



Use grunt to automate daily dev tasks, including your's application web performance, via these great tools:

Stargazers over time

Stargazers over time