axe accessibility scanner
axe is an open-source accessibility-testing engine from Deque Systems, embedded in browser extensions, CI pipelines, and tools that evaluate pages against WCAG accessibility rules. When run in an automated or hosted mode it fetches and renders a page to analyse its accessibility, rather than indexing content for search. It typically runs on your own pages, on demand, as part of accessibility QA.
What this means
axe-core is a widely used accessibility-rules engine. It powers the axe browser extension and is embedded in test frameworks and hosted scanners, evaluating a rendered page for WCAG issues such as missing alt text, contrast problems, and ARIA misuse.
When run interactively in a browser, axe may not generate distinct server requests. In automated or hosted modes — CI runners, headless browsers, hosted scanning — it fetches and renders the page, which can appear in logs. This is accessibility analysis, not search indexing.
How it identifies itself
Automated axe runs typically use a headless browser, so the user-agent often reflects that browser plus any tool-specific token the runner sets. Match on your testing tool's configured identity and correlate with your QA/CI schedule rather than expecting a single fixed token.
Because user-agents are configurable and copyable, treat them as claims. An expected axe run should align with a test you scheduled.
- Engine: axe-core (Deque) accessibility rules
- Modes: browser extension, CI, headless, hosted scanners
- User-agent reflects the headless browser plus tool token
robots.txt considerations
Accessibility testing is usually run against your own pages, so you may intentionally allow it regardless of robots.txt. Where a hosted scanner exposes a documented token, you can target it in robots.txt to express a preference.
robots.txt is honoured by compliant crawlers and is not an access control. For your own accessibility QA, restricting the tool would only hinder your testing.
How it appears in analytics and logs
An automated axe fetch means an accessibility test rendered and analysed your page against WCAG rules, usually as part of your own QA or CI. It is accessibility-testing bot traffic, not a human visit and not a search-index crawl.
Diagnostic use case
Recognise automated axe accessibility checks in logs, confirm they correspond to your own QA or CI runs, and distinguish accessibility analysis from search indexing.
What WebmasterID can help detect
WebmasterID classifies automated axe runs server-side as accessibility-testing bot traffic and surfaces them on the bot-intelligence surface, so QA checks stay separate from human analytics.
Common mistakes
- Mistaking your own accessibility QA run for an external search or attack crawler.
- Expecting a single fixed axe user-agent when automated runs use headless browsers.
- Counting accessibility-test fetches as human visits in analytics.
Privacy and accuracy notes
Identification uses only the request user-agent and rendering context. No visitor identity is involved. WebmasterID records the fetch as a bot event, separate from human analytics, and never attaches it to a profile.
Related pages
- WAVE accessibility crawler
WAVE is a web accessibility evaluation tool from WebAIM that analyses pages for accessibility and WCAG issues, available as a hosted checker, browser extension, and API. Its hosted and API modes fetch a page to evaluate its accessibility and report errors and alerts. It is an accessibility-evaluation tool, typically run on pages you want to test, rather than a search engine indexing content.
- Lighthouse and PageSpeed Insights fetchers
Lighthouse is Google's open-source page-quality auditing tool, and PageSpeed Insights is the hosted service that runs Lighthouse audits and reports field and lab performance data. Both fetch a page on demand to measure it, not to index it for search. Their fetches are user-triggered performance audits and appear in logs as a single page load with related resource requests, not a crawl.
- Web-performance fetchers overview
Web-performance tools — Lighthouse, PageSpeed Insights, GTmetrix, WebPageTest and similar — load a page on demand to measure speed, rendering, and resource behaviour. They are neither search crawlers nor human visitors: they are user-triggered measurement automation. Reading them correctly keeps performance audits out of audience metrics and out of search-crawl coverage.
- Website observability
See automated testing tools reaching your site, recorded server-side.
Sources and verification notes
- Deque — axe-core accessibility engineOpen-source WCAG accessibility-rules engine; runs in browser, CI, and headless modes.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.