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

YandexImageResizer

YandexImageResizer is a specialized utility bot from the Russian search engine Yandex. Its purpose is to retrieve and process images from websites to create optimized, resized versions (e.g., thumbnails) for display across Yandex's services, such as in search results. This helps improve performance and user experience by ensuring images load quickly and are appropriately formatted.

What is YandexImageResizer?

YandexImageResizer is a utility bot from Yandex that identifies, retrieves, and processes images from websites. It is a specialized crawler that focuses only on image content. The bot identifies itself with the user-agent string Mozilla/5.0 (compatible; YandexImageResizer/2.0; +http://yandex.com/bots). Unlike general-purpose crawlers, it has a very specific technical function: to resize images for different display contexts within Yandex services.

Why is YandexImageResizer crawling my site?

YandexImageResizer is visiting your website to process images that are or will be displayed in Yandex's services, such as in search results or image search. If your site's images appear in Yandex search, the bot will visit to process them. The frequency of visits depends on how often your content appears in Yandex search and how frequently your image content changes. This is a legitimate activity as part of Yandex's service.

What is the purpose of YandexImageResizer?

The purpose of YandexImageResizer is to optimize images for display across various Yandex services. When Yandex needs to show an image thumbnail or an optimized version of an image from a website, this bot processes the original, full-sized image into the appropriate format and size. This helps Yandex deliver a faster, more efficient user experience and reduces bandwidth consumption. For website owners, this processing can indirectly benefit your content's visibility within the Yandex ecosystem.

How do I block YandexImageResizer?

To prevent YandexImageResizer from accessing your site's images, 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: YandexImageResizer
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.