YandexAdditionalBot
Yandex documents YandexAdditionalBot as a robots.txt control, not a crawler. A Disallow rule under that token keeps already-indexed page content out of Search with Yandex AI responses; it makes no indexing requests and general robots.txt rules do not cover it. Verification is reverse DNS to yandex.ru, yandex.net or yandex.com plus forward DNS; Yandex publishes no IP list.
Mozilla/5.0 (compatible; YandexAdditionalBot/1.0; +http://yandex.com/bots)What YandexAdditionalBot does
Yandex's documentation lists two user agent strings, "Mozilla/5.0 (compatible; YandexAdditional/1.0; +http://yandex.com/bots)" and "Mozilla/5.0 (compatible; YandexAdditionalBot/1.0; +http://yandex.com/bots)", and accepts either name in robots.txt. The same documentation says the robot doesn't make indexing requests, so its main role is as a policy token. Yandex describes it as a way to process robots.txt so that page content does not appear in Search with Yandex AI responses. It applies only to pages the primary crawler, YandexBot, has already indexed.
Allowing the token changes nothing about how your pages are indexed; they remain subject to the primary crawler's rules. Disallowing a path under this token tells Yandex to keep that content out of its AI responses in Search while leaving ordinary search indexing alone. Yandex's own example is "User-agent: YandexAdditionalBot" followed by "Disallow: /cats/mycat.html". Because the token is scoped to AI responses, it is the documented way to opt a page out of that feature without removing it from Yandex search results.
Yandex says a change takes effect after its robots recrawl the page, typically within 2 to 14 days. The general robots.txt rules column for this token is marked No, meaning rules written for all user agents do not govern it; you must address the token by name. Yandex does not document any crawl volume or schedule for this token, and it does not say whether the token has any effect beyond Search with Yandex AI responses.
Operator note. This is a robots.txt control that applies to pages already indexed by the primary crawler and 'doesn't make indexing requests'. Both 'YandexAdditional' and 'YandexAdditionalBot' are accepted, and Yandex documents a UA string for each: 'Mozilla/5.0 (compatible; YandexAdditional/1.0; +http://yandex.com/bots)' and '...YandexAdditionalBot/1.0...'. The official example is 'User-agent: YandexAdditionalBot / Disallow: /cats/mycat.html', and a change takes effect after Yandex robots recrawl the page, typically 2-14 days. It does not take into account the general rules in robots.txt.
Controlling YandexAdditionalBot with robots.txt
YandexAdditionalBot is a policy token. It has no crawler of its own; it tells Yandex how content already fetched by its other crawlers may be used. Put it in robots.txt like any other token.
User-agent: YandexAdditionalBot
Disallow: /User-agent: YandexAdditionalBot
Allow: /Verifying a request is really YandexAdditionalBot
Anyone can put YandexAdditionalBot in a User-Agent header. Reverse DNS lookup on the requesting IP must return a host ending in yandex.ru, yandex.net or yandex.com, and a forward DNS lookup of that host must return the same IP. Yandex Webmaster also provides an IP address check tool.
host <request-ip>
# expect a hostname ending in yandex.ru, yandex.net, yandex.com
host <that-hostname>
# expect it to resolve back to <request-ip>Common questions
Should I block YandexAdditionalBot?
Only if you want your pages kept out of Search with Yandex AI responses. A Disallow rule under this token removes the listed pages from those AI answers per Yandex's documentation, while regular Yandex search indexing by YandexBot continues unchanged. If you are fine with AI responses quoting your content, no rule is needed.
Does YandexAdditionalBot crawl my site?
Yandex says it doesn't make indexing requests. It is a robots.txt control that applies to pages the primary crawler has already indexed. Yandex does list user agent strings for YandexAdditional and YandexAdditionalBot, but the documentation does not describe any crawl volume or schedule for them.
How do I verify YandexAdditionalBot?
Use the same method Yandex documents for all its robots. Run a reverse DNS lookup on the IP; the host must end in yandex.ru, yandex.net or yandex.com. Then run a forward lookup on that host and confirm it returns the same IP. Yandex Webmaster also has an IP address check tool. No IP ranges are published.
Sources
Every fact on this page was checked against Yandex's own documentation, listed below, and re-checked by a second reviewer before publication. Reviewed September 2026.
Related crawlers
This registry documents how operators describe their own bots so site owners can identify and control them. It does not publish third-party IP lists or guess at undocumented behaviour. To see how your own site responds to automated visitors, the bot detection scanner reads a URL's live response and names the protection it finds.