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

BingPreview

BingPreview is a specialized web crawler from Microsoft that generates the visual page previews shown in Bing's search results. Unlike the main bingbot, which indexes content, BingPreview's sole job is to render web pages—executing JavaScript and CSS—to assess their appearance, particularly on mobile devices. This helps ensure that search result previews are accurate and supports Microsoft's mobile-first indexing strategy.

What is BingPreview?

BingPreview is an official web crawler from Microsoft, distinct from the main bingbot. Its specific function is to render web pages to create the snapshot previews that appear in Bing search results and other Microsoft services. The crawler is capable of fully rendering a page, including executing JavaScript and CSS, to accurately assess how it appears on different devices, especially mobile phones. It identifies itself with user-agent strings such as Mozilla/5.0 (...); BingPreview/1.0b for desktop and includes identifiers like iPhone for mobile simulations. The bot operates from Microsoft's IP ranges and is designed to be respectful of server resources.

Why is BingPreview crawling my site?

BingPreview is visiting your website to generate a visual preview that may be displayed in Bing's search results or Microsoft apps. Its presence indicates your content is being evaluated for its presentation quality. The crawler tends to focus on pages that already have some visibility in Bing or that have frequently updated content. It is particularly interested in a site's mobile-friendliness and rendering quality. This is a legitimate and authorized activity from Microsoft, and the bot respects standard robots.txt directives.

What is the purpose of BingPreview?

The primary purpose of BingPreview is to generate the visual snapshots of web pages that appear in Bing's search results. By rendering pages exactly as a user would see them, BingPreview helps provide more helpful and accurate search results. The bot is also a key component of Microsoft's mobile-first indexing strategy, as it evaluates how well websites perform and render on mobile devices. For website owners, this can be beneficial, as a well-rendered site may see improved visibility and higher click-through rates from Bing search users.

How do I block BingPreview?

If you wish to prevent BingPreview from generating snapshots of your pages, you can block it using your robots.txt file. Note that this may result in generic or no previews appearing for your site in Bing search results.

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

User-agent: BingPreview
Disallow: /

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

Reverse IP lookup technique

To verify user-agent authenticity, you can use host linux command two times with the IP address of the requester.

```
> host IPAddressOfRequest
```
This command returns the reverse lookup hostname (e.g., 4.4.8.8.in-addr.arpa.).

> host ReverseDNSFromTheOutputOfFirstRequest

If the output matches the original IP address and the domain is associated with a trusted operator (e.g., Bing), 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.