About a11ychk-bot
a11ychk-bot is the browser the web accessibility service A11y Check uses to audit pages. If you see it in your server logs, someone asked this service to check your site's accessibility. The service's MCP server also uses this name when it fetches robots.txt while collecting representative pages (crawl_sample).
What it does
Given a site address, it picks representative pages (about 30 at most) from sitemap.xml and links on the home page, opens each in headless Chromium, and checks it against WCAG 2.2 and KWCAG 2.2.
It does not index for search or harvest content. Results go into the report of the user who requested the audit; no-login quick checks keep only the domain and summary figures as service statistics. A user who verified ownership of the site can embed the summary score as a badge, and it appears in the public directory if they choose to publish.
When it visits
Only when a user runs an audit. Each audit opens 2 pages at a time by default (up to 3 depending on configuration); if several users audit the same site at once, that adds up. Images and video are not downloaded.
Recurring daily, weekly or monthly audits can be enabled only by users who have verified ownership of the site.
User-Agent
The audit browser sends the User-Agent below. Match on the a11ychk-bot token to allow or block it in firewall or bot rules. One exception: the site access check requests the entered address once regardless of robots.txt, and may request it once more with a regular browser User-Agent to compare bot blocking.
Mozilla/5.0 (compatible; a11ychk-bot/0.1; +https://a11ychk.com/bot)Blocking visits
We follow robots.txt. With the rules below, apart from requests that check robots.txt and the address the audit was requested for, we will not open your pages even when an audit is requested. Pages a user enters by hand are skipped too if robots.txt blocks them. Without an a11ychk-bot group, the User-agent: * group applies.
User-agent: a11ychk-bot
Disallow: /Site owner exception
When a user who has verified ownership of the site (via DNS, meta tag or file) enters pages of that site by hand, we audit them regardless of robots.txt, so owners can check staging sites that block bots.
Contact
If visits cause problems, let us know at isaaceryn@gmail.com.