What is stormcrawler?

Apache StormCrawler is a toolkit for building web crawlers, programs that systematically visit and download pages from the internet. It's designed for projects that need to crawl large numbers of websites quickly and reliably, whether that's for a search engine, a data pipeline, or a monitoring system. At a high level, the project provides a set of building blocks that handle the common challenges of web crawling: deciding which URLs to visit, fetching pages efficiently, parsing their content, and following links to discover more pages. It runs on Apache Storm, which is software that lets you distribute work across many computers so you can scale up to handle bigger crawling jobs. You configure the crawler through text files that specify things like which sites to crawl and how to identify your crawler to the websites you're visiting. The main audience is developers or organizations building systems that need to collect web content at scale. A startup building a specialized search engine, a company that monitors competitor pricing across thousands of product pages, or a research team collecting data from news sites would all be typical users. It's not a tool for someone who just needs to scrape a single page, it's built for ongoing, large-scale crawling operations. Getting started requires some technical setup. You need Java 17 or higher, Apache Maven (a build tool for Java projects), and Apache Storm itself. The project provides a template generator that creates a starter project with sensible defaults, including the configuration files and a basic crawling setup. From there, you customize the configuration to target the sites you want to crawl. The project is mature and backed by the Apache Software Foundation, which means it has an established community, documentation, and even companies offering commercial support. It's written primarily in Java and released under the Apache License, so it's free to use and modify.