About Our Scanner

The A11y Pulse scanner is the automated browser that visits web pages to check them for accessibility issues. If you’ve seen A11y Pulse in your server logs or firewall reports, this page explains what that traffic is and how to allow it.

What the scanner does

• It only visits pages our customers have added. The scanner loads the pages that an A11y Pulse customer has added to their account, on the schedule they’ve chosen.
• It loads pages like a real browser. The scanner runs a recent version of Chrome, so it loads your page’s HTML, stylesheets, scripts, images, and fonts, just as a visitor’s browser would.
• It checks the page, then leaves. Once a page has loaded, the scanner runs automated accessibility checks, such as color contrast, keyboard focus, and text spacing (see A11y Pulse Audits). It takes a screenshot, then closes the page. It doesn’t submit forms or change data, unless a customer has written a script to log in or set up the page first.

When a customer asks A11y Pulse to find pages on their site, a separate, lightweight crawler follows links from their homepage. It only downloads HTML, and doesn’t load scripts, stylesheets, or images.

Identifying scanner traffic

The scanner uses a standard Chrome user agent, so the most reliable way to identify it is by IP address.

Scans for sites with the static IP feature come from this address:

134.199.187.185

This list is also published in a machine-readable format at https://www.a11ypulse.com/docs/static-ips.json. It uses the same prefix format as other published crawler IP lists, so firewalls and bot management tools can read it automatically.

Scans for sites without the static IP feature, and all crawler traffic, come from a changing pool of cloud addresses, and aren’t listed.

Allowing the scanner through your firewall

If your site uses a firewall, WAF, or bot protection service (such as Cloudflare), it may block the scanner or show it a challenge page instead of your content. When that happens, A11y Pulse checks the challenge page rather than your site.

To let the scanner through:

1. Ask us to enable the static IP feature for your account.
2. Add the address above to your firewall or bot protection allowlist.

Contact us

If you have questions about scanner traffic on your site, or think the scanner is misbehaving, email [email protected].