Top Web Crawling Libraries for Java

jsoup Java HTML Parser · jsoup is a Java library for working with real-world HTML. It provides a very convenient API for fetching URLs and extracting and manipulating data, using the best of HTML5 DOM methods and CSS selectors. jsoup implements the WHATWG HTML5 specification, and parses HTML to the same DOM as modern browsers do.

edu.uci.ics:crawler4j · Open Source Web Crawler for Java

Apache Nutch · Nutch is an open source web-search software. It builds on Hadoop, Tika and Solr, adding web-specifics, such as a crawler, a link-graph database etc.

storm-crawler-archetype