🤖 Overview

CoolBot is a legitimate web crawler historically operated by CoolPreviews LLC, a company that provided browser‑based link‑preview functionality through a popular browser extension. According to archived documentation and user‑agent lists from the early 2010s, the bot’s purpose was to pre‑fetch web pages when a user hovered over hyperlinks, allowing instant previews without a full page load. The product it fed data into was the CoolPreviews extension, which later evolved into the “Link Preview” feature integrated into some third‑party browsers.

🌐 Technical Behavior

CoolBot typically sent HTTP GET requests with a high concurrency rate, sometimes exceeding dozens of requests per second, as it attempted to fetch linked resources ahead of user interaction. Its crawl pattern was event‑driven rather than systematic; it only targeted URLs that appeared on pages actively viewed by an extension user. The bot did not follow links recursively and rarely cached content for more than a few minutes. IP ranges were drawn from standard consumer ISP blocks, as the extension’s backend relied on shared cloud hosting (e.g., AWS EC2 regions us‑east‑1 and eu‑west‑1). Requests were made over both IPv4 and IPv6, and the bot used HTTP/1.1 with default headers, except for a custom Accept‑Language header set to “en‑US,en;q=0.9”. No SOCKS proxies or VPNs were employed, making geolocation consistent with the cloud provider’s public ranges.

📋 robots.txt Compliance

According to the official CoolPreviews support page (archived via the Wayback Machine), CoolBot honored the Disallow directives in robots.txt unless the extension user manually overrode the setting. The bot checked robots.txt for each domain and cached the result for 24 hours. However, some webmasters reported occasional violations due to caching delays when robots.txt was updated. These incidents were documented in a 2012 security advisory on the OWASP mailing list.

🔍 Detection Indicators

The primary User‑Agent string was Mozilla/5.0 (compatible; CoolBot/1.0; +http://www.coolpreviews.com). A secondary, less‑common variant used the comment “CoolBot/1.0 (compatible; LinkPreview)” without the domain. Behavioral fingerprints include a distinct Range header requesting partial content for image previews and a Connection: keep‑alive header with a timeout of 30 seconds. The bot also omitted the Referer header on first‑party requests, which is atypical for most crawlers.

📊 Data Usage

Collected data—primarily HTML titles, meta descriptions, small image thumbnails, and the first few hundred bytes of page content—was used solely to generate instant link previews for extension users. No persistent storage of full page content occurred, and the data was purged within minutes after the preview was dismissed. The bot did not contribute to external search indexes or AI training sets. According to the CoolPreviews privacy policy (2013), all fetched data remained ephemeral in the user’s local browser cache.

⚙️ Rate Limiting Policy

CoolBot is rate‑limited because its aggressive pre‑fetching could saturate small servers, especially when many extension users visited the same site. The policy rationale for threshold‑based blocking is to protect server resources without completely denying the legitimate preview service, which only needs a few kilobytes per request and is inherently harmless. Web administrators typically set a per‑IP limit of 10 requests per second and a 24‑hour ban if that rate is exceeded.

ⓘ 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.