The 5 best open source web crawlers in 2024

Open source web crawlers are powerful tools for extracting data from websites at scale. They allow developers to customize and extend the crawling capabilities to suit their specific needs. In this article, we'll take a look at the 5 best open source web crawlers available in 2024.

1. Scrapy

Scrapy is the most popular open source web crawling framework, with over 45,000 stars on GitHub. It is written in Python and provides a powerful and flexible platform for building web crawlers. Some key features of Scrapy include:

• Support for extracting data using CSS and XPath selectors

• Built-in support for handling cookies, authentication, and sessions

• Extensible through middlewares and pipelines

• Asynchronous requests for high performance

Here's an example of a simple Scrapy spider:

import scrapy

class ExampleSpider(scrapy.Spider):

name = 'example'

start_urls = ['http://example.com']

def parse(self, response):

for quote in response.css('div.quote'):

yield {

'text': quote.css('span.text::text').get(),

'author': quote.css('small.author::text').get(),

}

2. Heritrix

Heritrix is an open source, extensible, web-scale, archival-quality web crawler written in Java. It was developed by the Internet Archive and is designed for archiving websites. Some notable features of Heritrix include:

• Modular and extensible architecture

• Support for multiple protocols (HTTP, HTTPS, FTP)

• Respect for robots.txt and other exclusion directives

• Web-based user interface for monitoring and control

3. Apache Nutch

Apache Nutch is a highly extensible and scalable open source web crawler written in Java. It has a modular architecture that allows developers to create plugins for parsing, data retrieval, querying and clustering. Key features of Nutch include:

• Distributed architecture for scaling

• Support for parsing various document formats (HTML, PDF, etc.)

• Integration with Apache Hadoop and Apache Solr

• Configurable through a set of properties files

4. Crawler4j

Crawler4j is an open source web crawler written in Java. It provides a simple interface for crawling the web, and is designed to be scalable and efficient. Some features of Crawler4j include:

• Multi-threaded crawling

• Configurable maximum crawl depth and maximum pages to fetch

• Support for custom politeness delays between requests

• Extensible through plugins and event listeners

Here's an example of using Crawler4j:

public class MyCrawler extends WebCrawler {

@Override

public boolean shouldVisit(Page referringPage, WebURL url) {

String href = url.getURL().toLowerCase();

return !FILTERS.matcher(href).matches() && href.startsWith("https://example.com/");

}

@Override

public void visit(Page page) {

String url = page.getWebURL().getURL();

System.out.println("Visiting: " + url);

}

}

5. Apify SDK

Apify SDK is a scalable open source library for crawling websites using Node.js and headless Chrome. It provides a high-level API for defining crawlers and handling large crawls. Key features include:

• Automatic scaling of crawling based on system resources

• Support for handling dynamic content through Puppeteer

• Configurable request queues and result storage

• Integration with Apify Cloud for running crawlers at scale

Here's a simple example using Apify SDK:

const Apify = require('apify');

Apify.main(async () => {

const requestQueue = await Apify.openRequestQueue();

await requestQueue.addRequest({ url: 'https://example.com' });

const crawler = new Apify.PuppeteerCrawler({

requestQueue,

handlePageFunction: async ({ page }) => {

const title = await page.title();

console.log(`Page title: ${title}`);

},

});

await crawler.run();

});

Summary

In this article, we looked at the 5 best open source web crawlers available in 2024. Scrapy is the most popular and feature-rich crawling framework, while Heritrix is designed for archiving websites at scale. Apache Nutch provides a highly extensible and scalable architecture, and Crawler4j offers a simple interface for Java developers. Finally, Apify SDK leverages headless Chrome and automatic scaling for powerful crawling.

The choice of web crawler depends on your specific requirements, but these open source options offer a solid foundation to build upon. By customizing and extending these tools, developers can create robust web crawling solutions to extract data efficiently.