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npm version Build Status Dependency Status

Easy accessibility audits powered by the Chrome Accessibility Tools


$ npm install --global a11y

PhantomJS, which is used for generating the screenshots, is installed automagically, but in some rare cases it might fail to and you'll get an Error: spawn EACCES error. Download PhantomJS manually and reinstall a11y if that happens.

CLI usage

Run an audit against a URL:

$ a11y

Or multiple URLs:

$ a11y


Also works fine against localhost:

$ a11y localhost:9000

And local files:

$ a11y index.html

Even with glob patterns:

$ a11y '**/*.html'


Query help:

$ a11y --help

Customise viewport size

Type: string
Default: 1024x768

$ a11y --viewport-size=800x600

Set a custom delay before capturing the page

Type: number (seconds)
Default: 1

$ a11y --delay=5

Useful when the site does things after load that you want to capture.

Verbose mode:

$ a11y <url> --verbose

Write audit to file:

$ a11y <url> > audit.txt

Module usage

Audit a remote URL and generate an accessibility report:

const a11y = require('a11y');

a11y('', (err, reports) => {
    const audit = reports.audit; // `a11y` Formatted report
    const report =; // DevTools Accessibility Audit formatted report

Work with the output of reports.audit:

const a11y = require('a11y');

a11y('', (err, reports) => {
    for (const report of reports) {
        // Result will be PASS, FAIL or NA
        if (report.result === 'FAIL') {
            // el.heading
            // el.severity
            // el.elements

Passing options:

const a11y = require('a11y');

const options = {
    viewportSize: '800x600'

a11y('', options, (err, reports) => {
    // ...

Currently, the only suported option is:

  • viewportSize (String in format WIDTHxHEIGHT, eg 800x600)

Interpreting results

To interpret how to fix individual issues in an audit, see the Audit Rules section of the Accessibility Developer Tools project.

Per the Accessibility Developer Tools, the results in an audit may be one of three types:

  • PASS - implies that there were elements on the page that may potentially have failed this audit rule, but they passed. Congratulations!
  • FAIL - This implies that there were elements on the page that did not pass this audit rule. This is the only result you will probably be interested in.
  • NA - This implies that there were no elements on the page that may potentially have failed this audit rule. For example, an audit rule that checks video elements for subtitles would return this result if there were no video elements on the page.

Build-system integration

If you use Grunt, grunt-a11y is a task by João Figueiredo that uses a11y under the hood.


At this time, this module should be relatively reliable when auditing for accessibility issues in static sites.

We are actively working on exploring support for complex web-applications, including those using JavaScript libraries such as Polymer, Angular and React/Flux. We hope to bring this work to the main master branch once it is considered stable.