YandexOntoDBAPI
Yandex operates YandexOntoDBAPI, which Yandex describes as the information card robot that downloads dynamic data. It has its own robots.txt token, but Yandex says general robots.txt rules do not apply to it, so robots.txt support is partial. Site owners verify requests by reverse DNS to yandex.ru, yandex.net or yandex.com with forward confirmation; Yandex documents no IP ranges.
Mozilla/5.0 (compatible; YandexOntoDBAPI/1.0; +http://yandex.com/bots)What YandexOntoDBAPI does
The bot identifies itself in logs as Mozilla/5.0 (compatible; YandexOntoDBAPI/1.0; +http://yandex.com/bots). The string carries version 1.0. Yandex's only documented description of its purpose is that it is the information card robot that downloads dynamic data. Yandex does not expand on what an information card is or which data the bot downloads, so a site owner should expect a Yandex-identified request without further documented context.
Yandex states that general robots.txt rules do not apply to YandexOntoDBAPI, so its robots.txt support is partial. The bot has its own User-agent token, YandexOntoDBAPI, and that token is the documented way to address it. Yandex does not document what allowing or blocking the bot changes for a site beyond the stated purpose of downloading dynamic data for information cards. Site owners who want to refuse it have the token to work with, and should check the result rather than assume the rule takes effect.
To verify a request, reverse-resolve the source IP and check that the hostname ends in yandex.ru, yandex.net or yandex.com, then resolve that hostname forward and confirm the answer is the original IP. A request whose reverse lookup fails or resolves outside those suffixes does not pass Yandex's documented check. Yandex Webmaster also has an IP address check tool for this. Yandex documents no IP range list for the bot.
Operator note. It does not take into account the general rules in robots.txt.
Controlling YandexOntoDBAPI with robots.txt
Use the token YandexOntoDBAPI in robots.txt. Yandex documents limits on how this bot applies robots.txt; see the operator note.
User-agent: YandexOntoDBAPI
Disallow: /User-agent: YandexOntoDBAPI
Allow: /Verifying a request is really YandexOntoDBAPI
Anyone can put YandexOntoDBAPI 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 YandexOntoDBAPI?
Yandex documents the bot only as the information card robot that downloads dynamic data, and it does not describe what a site loses by blocking it. You can address it with the YandexOntoDBAPI User-agent token, but Yandex says general robots.txt rules do not apply to it, so test the result rather than assume the rule works.
Does YandexOntoDBAPI obey robots.txt?
Partially. Yandex lists a dedicated YandexOntoDBAPI User-agent token and states that general robots.txt rules do not apply to this bot. The documentation does not go into more detail about which directives it follows.
How do I verify YandexOntoDBAPI?
Reverse-resolve the source IP and check that the hostname ends in yandex.ru, yandex.net or yandex.com, then forward-resolve that hostname and confirm it returns the same IP. The Yandex Webmaster IP address check tool does the same check. Yandex documents no IP range file for this bot.
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.