YandexAdditional
Yandex · AI search · robots.txt: Yes
A robots.txt control token, not a crawler that indexes: it decides whether pages Yandex has indexed may be used in Search with Yandex AI answers.
Block YandexAdditional
User-agent: YandexAdditional
Disallow: /Disallowing YandexAdditional keeps pages out of Yandex AI answers. Yandex says it applies to pages its primary crawler has indexed and makes no indexing requests, so it does not remove you from Yandex Search.
Allow YandexAdditional
User-agent: YandexAdditional
Allow: /An allow group only changes anything if a broader rule would block YandexAdditional. Under the robots.txt standard (RFC 9309, section 2.2.1) a crawler follows the group that names it and uses the User-agent: * group only when no group does — so this group lets it in even if your * group says Disallow: /. Token matching is case-insensitive.
Put these lines in /robots.txt at the root of each host (each subdomain has its own file). robots.txt is a request to well-behaved crawlers, not access control.
Already have a robots.txt? Paste it into the robots.txt checker to see whether it blocks YandexAdditional on a given path, and which line decides.
Facts
- Operator
- Yandex
- Purpose
- AI search index
It governs only whether pages Yandex has already indexed may appear in answers from Yandex AI, a feature of Yandex Search.
- Obeys robots.txt
- Yes. Yandex says to disallow YandexAdditional or YandexAdditionalBot (either token works) to keep pages out of Yandex AI answers; the change takes effect when the pages are recrawled, typically in 2–14 days. Yandex says robots like this one may ignore the general User-agent: * rules, and its robot table marks YandexAdditional as not taking them into account — so a Disallow under * does not opt you out; name the token.
- In your server logs
- Yandex lists "YandexAdditional/1.0" and "YandexAdditionalBot/1.0" user-agent strings and says the token makes no indexing requests of its own.
- How to verify it
- There is no YandexAdditional crawl to verify. For Yandex's robots, Yandex says to run a reverse DNS lookup, check the host name ends in yandex.ru, yandex.net or yandex.com, then run a forward lookup and confirm it returns the same IP. Yandex does not publish its robots' IP addresses.
What Yandex says
Quoted word for word from the operator's documentation.
“If you don't want information from your site to be used in Yandex AI answers, add a disallow directive for "YandexAdditional" or "YandexAdditionalBot" in the robots.txt file.”
“The change will take effect as soon as Yandex robots recrawl the page, which typically takes 2–14 days.”
“Yandex AI answers are generated automatically from pages that were indexed by Yandex.”
“Helps process robots.txt to prevent page content from appearing in Search with Yandex AI responses. Applies to the pages that have been indexed by the primary crawler. Doesn't make indexing requests.”
“A number of Yandex robots download web documents for purposes other than indexing. To avoid unintentional blocking by site owners, they may ignore the file's restrictive directives robots.txt designed for arbitrary robots (User-agent: *).”
“Takes into account the General rules specified in robots.txt”
“"Mozilla/5.0 (compatible; YandexAdditional/1.0;”
“All Yandex robots have names ending in yandex.ru, yandex.net or yandex.com. If the host name has a different ending, the robot does not belong to Yandex.”
“Use a forward DNS lookup to get the IP address corresponding to the host name. It should match the IP address used in the reverse DNS lookup.”
“Therefore, their list is not disclosed.”
Sources
- Yandex Webmaster Help: Search with Yandex AI — fetched and checked 2026-09-24
- Yandex Webmaster Help: How to check that a robot belongs to Yandex — fetched and checked 2026-09-24