Accessibility bots are bots that specifically check compliance for best accessibility practice. This involves basic checks for dynamic font size and legibility, suitable alt.text for images, keyboard navigation alternatives, support for assistive technology, and ensuring that e.g. CAPTCHA isn’t just constrained to visual and has some multi-media choices. Some bots specifically check against the Web Content Accessibility Guidelines (WCAG) - which is a list of criteria your website or mobile application may need to meet in order to be legally compliant in your country. Although most responsible webmasters at larger companies will always do their best to ensure maximum accessibility, many smaller sites aren’t aware of the issues, and / or don’t have the resources. However, there are many online accessibility checking scanners, that can automate reporting on the compliance process. There are also advocacy services that specifically target non-compliant sites. The bots will collect proof of non-compliance.
Yandex Accessiblity Bot
Major Russian portal and search engine Yandex accessiblity bot which downloads pages to check user accessibility. YandexAccessibilityBot ignores the general bot instructions in robots.txt so that it can download and check for accessible pages, but it can be specifically excluded by disallowing the agent YandexAccessibilityBot
Google Read Aloud
Webmasters wishing to ensure their websites are fully accessible will want to whitelist this bot. Google-Read-Aloud is the user agent for the Google Read Aloud service. This service enables reading web pages using text-to-speech (TTS). This service is activated when an end user has text to speech enabled and visits a page. Google Read Aloud is triggered by a user request. Google Read Aloud conserves bandwidth by caching page results, so you should not see more than one request every few hours for a given page. Google Read Aloud is not a web crawler: Google Read Aloud fetches only one page at a time, according to a user read request, and it doesn’t follow hyperlinks. Google Read Aloud acts as a direct agent of a human user, not as a robot, so it ignores robots.txt rules.