Published on 2025-08-07T06:18:08Z

YandexAdditionalBot

YandexAdditionalBot is a supplementary web crawler from the Russian search engine Yandex. It works alongside the main YandexBot to gather additional information from websites. Its purpose is to support and enhance Yandex's search index by collecting specific types of data, verifying content changes, or performing other specialized crawling tasks. Its presence is part of the normal operation of the Yandex search engine.

What is YandexAdditionalBot?

YandexAdditionalBot is a specialized web crawler from Yandex that performs additional crawling tasks to enhance its search and web services. It identifies itself in server logs with the user-agent string Mozilla/5.0 (compatible; YandexAdditionalBot/3.0; +http://yandex.com/bots). As a supplementary crawler to the main YandexBot, it may focus on specific types of content or perform specialized analysis.

Why is YandexAdditionalBot crawling my site?

YandexAdditionalBot is visiting your website to collect information that complements the data gathered by Yandex's primary crawlers. The frequency of visits depends on factors like your site's popularity and content update schedule. This is an authorized and standard activity for a major search engine.

What is the purpose of YandexAdditionalBot?

The purpose of YandexAdditionalBot is to support the Yandex search engine by gathering specialized or supplementary information. This helps Yandex improve its search results and provide more comprehensive information to its users. For website owners, having your content crawled by all of Yandex's bots can increase your visibility in their search results, which is particularly valuable for reaching audiences in Russia and other countries where Yandex has a significant market share.

How do I block YandexAdditionalBot?

To prevent YandexAdditionalBot from accessing your website, you can add a specific disallow rule to your robots.txt file. This is the standard method for managing crawler access.

To block this bot, add the following lines to your robots.txt file:

User-agent: YandexAdditionalBot
Disallow: /

How to verify the authenticity of the user-agent operated by Yandex?

Reverse IP lookup technique

To verify user-agent authenticity, you can use host linux command two times with the IP address of the requester.
  1. > host IPAddressOfRequest
    This command returns the reverse lookup hostname (e.g., 4.4.8.8.in-addr.arpa.). 
  2. > host ReverseDNSFromTheOutputOfFirstRequest
If the output matches the original IP address and the domain is associated with a trusted operator (e.g., Yandex), the user-agent can be considered legitimate.

IP list lookup technique

Some operators provide a public list of IP addresses used by their crawlers. This list can be cross-referenced to verify a user-agent's authenticity. However, both operators and website owners may find it challenging to maintain an up-to-date list, so use this method with caution and in conjunction with other verification techniques.