🤖 Overview

semanticdiscovery is a web crawler operated by Semantic Discovery Inc., a data-as-a-service company headquartered in New York, USA. The bot collects publicly available web content to build structured datasets for training large language models (LLMs), natural language processing (NLP) systems, and recommendation engines. Its primary product, the Semantic Discovery Platform, ingests crawled data to generate knowledge graphs, semantic embeddings, and domain-specific corpora used by enterprise AI teams. The crawler was first publicly documented in early 2023 and is distinct from common search-engine bots, focusing on high-quality textual and metadata extraction rather than full-page indexing.

🌐 Technical Behavior

The bot uses an asynchronous, multi-threaded architecture that spreads requests across a pool of rotating IP addresses sourced from Amazon Web Services (AWS) and DigitalOcean, with CIDR ranges including 52.84.0.0/15 and 168.245.0.0/16 (based on observed traffic patterns). It crawls at a variable rate, typically between 10 and 30 requests per second on a single domain, scaling down when Retry-After headers are received. The bot supports HTTP/1.1 and HTTP/2 protocols and sends a User-Agent string of Mozilla/5.0 (compatible; SemanticDiscovery/2.0; +https://semanticdiscovery.com/bot). It parses sitemap.xml files aggressively and respects Last-Modified headers to avoid re-crawling unchanged content. The crawler does not execute JavaScript, focusing exclusively on static HTML, CSS, and raw text extraction.

📋 robots.txt Compliance

According to official documentation on semanticdiscovery.com/bot, the crawler fully obeys robots.txt Disallow directives and will not revisit a blocked path for at least 30 days. The bot also respects Crawl-Delay directives with a minimum delay of 1 second. However, if a site does not return a robots.txt or returns a 503 status, the crawler may proceed with reduced rate.

🔍 Detection Indicators

Primary detection is via the User-Agent string: Mozilla/5.0 (compatible; SemanticDiscovery/2.0; +https://semanticdiscovery.com/bot). Additional behavioral fingerprints include a Via header containing SemanticDiscovery-Cache and a X-Forwarded-For that often contains AWS Elastic IPs. The bot also sends a custom header X-SemanticDiscovery-Version: 2.0. Reverse DNS lookups on its IPs resolve to *.semanticdiscovery.com or ec2-*.compute.amazonaws.com.

📊 Data Usage

Collected data is used exclusively for training proprietary NLP models, constructing domain-specific knowledge bases, and powering enterprise semantic search applications. Semantic Discovery does not resell raw crawled data but provides API access to curated, deduplicated datasets via its platform. The company publishes a Data Usage Policy at github.com/semanticdiscovery/data-policy that details retention (up to 12 months) and opt-out procedures.

⚙️ Rate Limiting Policy

Rate limiting is recommended because the bot can issue bursts of up to 50 requests in 5 seconds, which may degrade server performance if left unthrottled. Organizations should implement threshold-based blocking (e.g., 100 requests in 60 seconds from any SemanticDiscovery IP) to balance data accessibility with resource protection, as documented in the bot’s official rate-limit guidance.

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