What is BingPreview?

BingPreview is a specialized web crawler operated by Microsoft that renders web pages to generate previews for Bing's search engine and associated services. Launched around 2012, this crawler is distinct from Microsoft's primary indexing bot (Bingbot). BingPreview focuses specifically on evaluating how websites appear across different devices, with particular emphasis on mobile rendering.

The crawler identifies itself through user agent strings that typically follow this format: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534+ (KHTML, like Gecko) BingPreview/1.0b for desktop crawling. For mobile device simulation, it uses variants like Mozilla/5.0 (iPhone; CPU iPhone OS 7_0 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53 BingPreview/1.0b.

BingPreview's primary function is to fully render web pages—executing JavaScript and CSS—to assess how they appear on various devices. This rendering capability allows Microsoft to evaluate responsive design implementations, generate accurate search result previews, and ensure compatibility across platforms. The crawler operates from Microsoft's IP ranges (typically within the 40.77.0.0/16 block), and tends to limit its concurrent requests to respect server resources.

Why is BingPreview crawling my site?

BingPreview visits websites to generate visual previews that appear in Bing search results and Microsoft's app ecosystem. If you're seeing this crawler in your logs, it means your content is being evaluated for presentation quality in Bing's search interface.

The crawler typically focuses on pages that already rank in Bing search results or those with frequently updated content. It's particularly interested in assessing mobile-friendliness and rendering quality. BingPreview may visit more frequently if your site has strong visibility in Bing search results or if you've recently made significant design changes.

Crawling by BingPreview is authorized and legitimate activity from Microsoft. Its visitation patterns depend on your site's popularity in Bing search results, frequency of content updates, and mobile compatibility metrics. The crawler respects standard web protocols and robots.txt directives.

What is the purpose of BingPreview?

BingPreview serves multiple functions within Microsoft's search ecosystem. Its primary purpose is to generate visual previews of web pages that appear in Bing search results and Microsoft apps. By rendering pages as they would appear to users, BingPreview helps Bing provide more accurate and helpful search results.

The crawler supports Microsoft's mobile-first indexing strategy by evaluating how websites perform on mobile devices. It assesses responsive design implementations, detects mobile-specific content delivery, and ensures that search results accurately represent what users will experience.

For website owners, BingPreview's activity can be beneficial as it helps ensure your content is properly represented in Bing's search results. Sites that render well across devices may see improved visibility and click-through rates from Bing search. The crawler's evaluation of your site's mobile compatibility can indirectly influence your performance in mobile search rankings.

How do I block BingPreview?

BingPreview respects the robots.txt protocol, making it straightforward to control its access to your site. If you wish to block BingPreview from crawling your entire site, you can add the following directives to your robots.txt file:

User-agent: BingPreview
Disallow: /

If you prefer to allow BingPreview but want to manage its crawl rate to reduce server load, you can use the Crawl-Delay directive:

User-agent: BingPreview
Crawl-Delay: 10

This instructs BingPreview to wait 10 seconds between requests, which can help manage server resources. You can also block specific directories or file types while allowing access to the rest of your site:

User-agent: BingPreview
Disallow: /private-directory/
Disallow: /wp-admin/

Blocking BingPreview may prevent your pages from appearing with accurate previews in Bing search results, potentially reducing click-through rates from Bing users. If you're experiencing excessive crawling, adjusting the Crawl-Delay parameter is often a better approach than blocking the crawler entirely. For more granular control, you can also manage BingPreview through Bing Webmaster Tools, which allows you to set crawl rate preferences and monitor crawl activity.

BingPreview