The rapid growth of Internet data has led to an increasing demand for web crawlers among enterprises, developers, and individuals. Whether it is market research, competitive analysis, or preparing data for machine learning, web crawlers are indispensable tools. This article will briefly introduce the concept of web crawlers, analyze the difference between it and web crawling, and recommend the top 5 free web crawler tools in 2024 to help you quickly get started with data collection.

What is a web crawler?

A web crawler, also known as a spider, is an automated program or script that can browse web pages and extract the required data. Crawlers simulate user browsing behavior by sequentially accessing the hyperlinks of a website, downloading and parsing content page by page, and are widely used in search engines, data collection, information monitoring, and other fields.

Its working principle is simple. It starts with a web page, parses all the links, visits and repeats this process to achieve recursive data crawling. Web crawlers can help website owners find SEO problems and increase organic traffic, but many companies use anti-crawler technology (such as CAPTCHA, rate limiting, etc.) to protect public data. Crawlers deal with these obstacles by optimizing functions.

Web crawlers vs. web scraping

Although web crawlers and web scraping are often used interchangeably, there are significant differences between the two. Web crawlers focus on extensive web browsing and link tracking, and are usually used by search engines to index a large number of web pages and analyze the entire website content. In contrast, web scraping focuses on extracting structured data from specific websites, such as product information or user reviews, and is widely used in business intelligence gathering. The goal of crawlers is to traverse the entire Internet, while crawlers are more precise, extracting specific information and forming structured data. In short, crawlers focus on scope, and scraping focuses on content.

Is web scraping legal?

Web scraping is legal, which is also the basis for Google and Bing to accurately rank millions of websites. However, although web crawlers are widely used in technology, the legal issues they involve cannot be ignored.

When performing web crawling, it is crucial to comply with national and global information security, online privacy and ethical standards. Generally speaking, it is prohibited to collect personally identifiable data without authorization. Therefore, in order to perform web crawling legally and compliantly, it is necessary to ensure compliance with relevant laws and protect user privacy.

Top 5 free web crawler tools recommended in 2024

• Scrapy
  

Scrapy is an open source web crawler framework written in Python, which is widely used in data mining and information extraction tasks.

Allow users to customize crawler behavior

Support concurrent request processing

Automatic deduplication function to avoid repeated crawling

Easy to expand

Applicable to: Developers with a certain programming foundation

Beautiful Soup

Unlike Scrapy, Beautiful Soup is more like an auxiliary tool for extracting required information from downloaded web pages.

Handles various broken web page structures

• Highly adaptable
  

Easy to use

Applicable to: Novice developers or users who only need to extract simple web page data

• Octoparse
  

Octoparse is a visual web crawler tool that does not require programming knowledge. Users only need to operate through the graphical interface, select the data to be crawled, and Octoparse will automatically generate and execute the crawler script.

Supports complex operations such as crawling dynamic web pages, handling paging, and logging in

• Visual interface
  

Suitable for non-technical users

Applicable to: Users who need to quickly build crawlers

• ParseHub
  

ParseHub is a feature-rich crawler tool that supports crawling AJAX websites and dynamic content.Crawlers can be configured without programming

Supports crawling complex websites

• Various export formats
  

Applicable to: Users who need to crawl complex web content

• WebHarvy
  

WebHarvy is a visual crawler tool under Windows, designed for users who do not have programming skills.

Easy to use

• Support image crawling
  

Applicable to: e-commerce users or users who need to crawl a large number of images

Summary

Web crawler tools play a vital role in the data-driven era. Whether you are a novice user or an experienced developer, you can choose the right tool according to your needs.