Abot
Fast and flexible C# framework for building customizable web crawlers
...It manages essential components such as multithreading, HTTP requests, scheduling, and link parsing so developers can focus on processing the collected data. Abot follows a modular architecture that allows developers to customize nearly every stage of the crawl process by implementing or replacing core interfaces. Abot exposes an event-driven model that enables applications to react to crawling events such as page completion or crawl restrictions. It also provides configuration options that control crawling behavior including concurrency limits, crawl delays, and request parameters. Designed to be lightweight and dependency-free, Abot runs without requiring external services or databases, making it easy to integrate.