🤖 Overview

btsearch is a legitimate web crawler operated by Microsoft Corporation as part of the Bing search engine infrastructure, specifically dedicated to collecting data for Bing’s travel and shopping verticals. First publicly documented in 2010 via Microsoft’s Webmaster Tools, this bot aggregates publicly accessible pricing, availability, and product information from e-commerce and travel websites, feeding directly into Bing’s search results and comparison features. Unlike the general-purpose Bingbot, btsearch is specialized for high-frequency, structured data extraction from pages with transactional content.

🌐 Technical Behavior

btsearch crawls using HTTP/1.1 and HTTP/2 protocols, typically launching 1–3 requests per second per host, though the rate may spike during initial discovery of new URLs. It prioritizes pages with clear schema markup (e.g., Product, Offer, Flight, Hotel) and avoids multimedia-heavy pages unless linked. Requests originate from Microsoft’s own AS8075 IP ranges, including blocks such as 40.77.0.0/16, 13.66.0.0/16, and 157.55.0.0/16, and it uses reverse DNS names ending in .msn.com or .search.msn.com. The bot fetches pages incrementally, using ETags and If-Modified-Since headers to reduce bandwidth, and respects the Crawl-delay directive when set in robots.txt. It does not execute JavaScript or load external resources like images, focusing solely on raw HTML and structured data.

📋 robots.txt Compliance

According to Microsoft’s official documentation on Bing Webmaster Tools, btsearch fully honors the Robots Exclusion Standard, including both Disallow and Crawl-delay directives. The bot checks for robots.txt before each crawl session and caches the file for up to 24 hours. Webmasters can specifically disallow btsearch by targeting the user-agent “btsearch” in their robots.txt file, as confirmed in Bing’s published list of crawler user-agents (https://www.bing.com/webmaster/help/which-crawlers-does-bing-use-8c184ec0).

🔍 Detection Indicators

The primary identifying header is the User-Agent string: btsearch/2.0 (compatible; btsearch; +http://www.bing.com/btsearch.htm), though older versions may appear as btsearch/1.0. Additional fingerprints include the Accept header set to “*/*” and the absence of Accept-Encoding unless explicitly negotiating. The bot’s IPs always resolve to the msn.com domain via reverse DNS, and it does not send a Referer header. Security analysts can verify requests by checking for these patterns in web server logs (source: Microsoft’s official crawler list).

📊 Data Usage

Collected data—such as product names, prices, hotel rates, flight schedules, and availability—is used exclusively to populate Bing Travel and Bing Shopping search results, not for AI training or language model improvement. The data is indexed and served to users as real-time comparison listings, often with direct links back to the original website. Microsoft does not resell this data to third parties; it solely enhances Bing’s vertical search features (Bing Webmaster Guidelines, 2023).

⚙️ Rate Limiting Policy

btsearch is rate-limited because its focused, high-volume crawls of transactional pages can overwhelm smaller e-commerce sites if uncontrolled. A threshold-based rate limiter (e.g., blocking the IP if it exceeds 5 requests per second for more than 30 seconds) is recommended to maintain server stability while still allowing the bot to index critical pricing data for Bing’s user base.

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