🤖 Overview

Msrabot is a web crawler operated by Microsoft, specifically by Microsoft Research and AI divisions, as documented on the official Microsoft bot page at https://www.microsoft.com/en-us/msrabot. Its primary purpose is to collect publicly available web content for training and improving Microsoft's AI models, including those powering Bing, Copilot, and Azure AI services. First observed in early 2023, this bot is distinct from msnbot and bingbot and focuses on large-scale data acquisition for research.

🌐 Technical Behavior

Msrabot performs HTTP/1.1 and HTTP/2 requests with a default crawl delay of approximately 0.5 to 2 seconds, though it may increase frequency during bulk indexing events. It uses a rotating pool of IP addresses from Microsoft’s AS8075 (Azure cloud), with ranges published in the Azure IP Ranges service tag. The bot requests both HTML pages and structured data like sitemaps, follows all links unless blocked, and respects noindex meta tags. It accepts gzip compression, prioritizes HTTPS, and supports TLS 1.2 and 1.3. Crawl windows typically align with off-peak hours for the target server, but no strict scheduling is guaranteed.

📋 robots.txt Compliance

Microsoft’s official documentation confirms that Msrabot fully respects robots.txt directives, including Disallow, Crawl-Delay, and Allow. The bot fetches the robots.txt file at the root of each domain before every crawl session and caches it for up to one hour. If a Disallow is present, the bot will not request any URLs under that path; this behavior is verified in Microsoft’s publicly posted crawling policies.

🔍 Detection Indicators

The primary User-Agent string is Msrabot/1.0 (often seen as Mozilla/5.0 (compatible; Msrabot/1.0; +https://www.microsoft.com/msrabot)). Additional identifying headers include From: [email protected] and a User-Agent field containing the bot name. Behavioral fingerprints include a consistent pattern of fetching /robots.txt first, then crawling URLs in breadth‑first order with a typical request rate of 5 to 20 requests per minute per IP.

📊 Data Usage

Collected data is used for training and fine‑tuning Microsoft’s large language models (LLMs), improving search capabilities in Bing, and enhancing AI assistants like Copilot. Microsoft states that publicly available content is processed to generate training datasets, but personally identifiable information is filtered out. No user data from authenticated sessions is collected, and the data may also contribute to Microsoft Research projects in NLP and web understanding.

⚙️ Rate Limiting Policy

Rate limiting is recommended for Msrabot because its crawl can become aggressive during large‑scale indexing, potentially impacting server performance. Many webmasters impose a threshold of 10–20 requests per second per IP before blocking or throttling, which balances the bot’s legitimate need for data with site stability. Microsoft encourages site owners to use Crawl-Delay in robots.txt or implement standard rate limits.

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the bots listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.