Comprehensive Guide to Web Crawling vs Web Scraping in 2024

Over 5 billion people used the internet, and each user generates data. It is a vast data source that anyone can gain insight. However, getting data from websites is not easy. There are different data extraction methods to gather data from multiple web sources. Web scraping and web crawling are two methods for extracting data. Both are used to collect information from websites. However, they differ in terms of their purposes and methods. 

To decide which is best for your needs or how to combine them for your web scraping project, you need to understand the differences between web scraping and web crawling.

This article aims to provide information regarding the differences between web scraping and web crawling; by diving into each important aspect, including what they are, how they work, their use cases, challenges, and best practices.

Definition: Web Crawling vs Web Scraping

What is web crawling?

Web crawling is the process of indexing all of the information on a web page by using bots, also known as crawlers or spiders. 

Some websites have indexing issues. It prevents web crawlers from indexing those pages. Google index coverage report shows which pages in your property are indexed and which are not. You can identify and resolve indexing issues on your website’s pages.

What is web scraping?

Web scraping, also known as web harvesting or web data extraction, is the process of extracting data from multiple websites. Web data can be collected manually (copying and pasting data from a web page into a spreadsheet) or automatically by using a web scraping tool.

How-to: Web Scraping vs Web Crawling

How does web scraping work?

The web scraping process mainly consists of 6 steps: 

1. You must first identify the target website and URL(s) you would like to scrape. 
2. Use proxy servers if the targeted website is well-protected and use anti-scraping techniques such as CAPTCHAs. In case using a proxy server to make a connection request to the target website, proxy server:
   • Receives your connection request and assigns a different IP address to mask your real IP address. 
   •  Forwards your connection request to the website using on behalf of your machine. 
   • Scraper gains access to the website using the IP address assigned by the proxy server.
3. Web scraper makes a connection request to the website. 
4. Enter target URL(s) into the scraper’s input field and run the scraper.
5. Scraper extracts required data from the target website. 
6. Download scraped data in the desired format, such as JSON, CSV, etc. 

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How does web crawling work?

1. Web crawler collects URL(s) like “aimultiple.com”  
2. Crawler fetches and parses the collected URLs.
   • Fetch URL(s): It is a data collection method that uses a script to make requests to data sources in order to retrieve required data from its source.
   • Parse URL(s): Crawler splits the URL string into its components. It makes accessing specific URL components such as hostname or pathname easier. 
3. Reviews all pages that correspond to the URL(s), every URLs, hyperlinks, and meta tags. 
4. Index all the information on every single page. 
5. Archive indexed data in a database. 
6. As the web crawler parses and fetches the URL, it will find new links embedded in the page. Then crawler will add those URLs to a queue to crawl later.

Use cases:  Web Crawling vs Web Scraping

You’re probably wondering how search engines decide and find which web pages are relevant to your searched keyword within minutes. The most common application for web crawlers is search engines. For instance, when you searched for web scraping vs. web scraping query, you most likely got search results in a tick. The process mainly consists of three stages, including: 

• Crawling 
• Indexing 
• Ranking 

For sure, there is advanced technology behind it. However, we will discuss how search engines benefit from web crawlers. Continuing with the previous example, when you search for web crawling vs. web scraping, the search engine crawls all of the internet’s web pages, including images and videos. Search engines use web crawlers to crawl all pages by following the links embedded on those pages. Web crawlers discover new links to other URLs as they crawl pages and add these discovered links to the crawl queue to crawl next. Websites are constantly updating or relocating their content. You need to revisit web pages to ensure that the indexed information is up to date. 

Businesses can leverage web scraping for multiple purposes, including:  

• Monitor competitors: Web scraping allows businesses to collect competitor data from e-commerce websites and social media platforms using keywords or URLs. For example, you can extract your competitors’ product data, such as prices, reviews, ratings, stock availability, etc., from e-commerce product web pages. Businesses can use scraped product data for price comparison, forecasting demand and improving product positioning. 
• Website testing: When businesses migrate their website to a new design or platform, some internal links may become broken. Broken links have a negative impact on the search engine rankings of a website. So, it is critical to identify and fix broken links as soon as possible. Web scraping enables website owners to check overall website quality and identify dead links on web pages. Web scraping is also used for localization testing to ensure the accuracy and suitability of website content across multiple geographies and languages.
• Lead generation: Web scraping enables businesses to extract data from Google Maps. Google Maps data helps companies identify local businesses in a specific area and provide contact information such as website address and email address to reach out. You can scrape data from Google Maps by using specific keywords. LinkedIn is another great source to generate leads for B2B and B2C companies. You can scrape individual public profiles or companies’ profiles on LinkedIn.

A quick tip: Assume your target company is large, with 10,000 or more employees on LinkedIn. Instead of searching through all profiles to find the best profile to reach out, search employees by title. Even if you filter the results by the title of the employee, you will get hundreds of profile results to scrape. To get the most relevant results and avoid scraping redundant information, you can follow these steps: 

1. Determine the company you want to target. 
2. Identify which products or services of the targeted company you want to highlight in your LinkedIn or email message. 
3. Search for the query using the “company name & product name” structure on LinkedIn. 
4. View “all filters” and narrow down your results (see Figure 1).  
5. Scrape the search result.

Figure 1: Search result for a specific query on LinkedIn

Challenges: Web Crawling vs Web Scraping

The technical challenges of web scraping and crawling are the same. These challenges include: 

Spider trap

Spider trap, also known as crawler trap, is used to mislead web crawlers to fetch malicious pages such as spam links. As the crawler fetches malicious pages, the malicious pages will dynamically generate their spam links and redirect the crawler to these spam links. The crawler will get stuck in those pages and enter an infinite loop.

Politeness

If your web crawler makes many requests frequently to the same URL, the web server will become overwhelmed and have difficulty responding to each request. You must limit the frequency of requests and only crawl allowed web pages by the website.

Robots.txt

Before crawling a website, you need to check the website’s robots.txt file to understand what cannot be crawled on the website and stick to the constraints defined by the website.It defines which URLs or content you can or cannot access. Robots.txt allows or denies access to URLs on a website to limit the crawl rate. When a website detects a web crawler, it will blacklist IP addresses to prevent their websites from being crawled. The web crawler can access only web pages permitted by the website.

IP blocking

IP blocking is a technique used by websites to protect their websites from being scraped. When you frequently make multiple connection requests to the same website without changing your IP address, the website will find your activities suspicious and block your IP address to prevent you from accessing the website’s content.

Best Practices: Web Crawling vs Web Scraping

Use proxy servers

Proxy servers are intermediaries between your machine and the target website to protect your identity. There are various types of proxies that you can utilize in your web scraping projects. You can read our comprehensive guide on proxies for web scraping to learn more about how they avoid IP bans and increase security. Here’s a quick overview of how proxy servers work: 

1. Client makes a connection request to the target website. 
2. Proxy server receives the request and assigns a new IP address to the client to hide their real IP address. 
3. Proxy server forwards the request to the target destination. 
4. The website responds to the connection request and provides the information requested.
5. Proxy server receives the information from the server on behalf of the client.

Read our in-depth guide on web scraping best practices to explore how to tackle web scraping challenges in more detail.

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Oxylabs offers different types of proxies that can be used for web scraping. You can use proxies for IP rotation, anonymity, geo-targeting, and concurrency.

Take advantage of user agents

User agents reduce the risk of being blocked while scraping websites. User agents allow the server you want to scrape to understand which browser, operating system, or device you are using. Each browser’s user agent string format is different. You will identify your ID in the way the browser’s user agent format you used in your connection requests. However, the server will detect and ban you if you make multiple requests to the server with the same user agent. To avoid being blocked, use a major browser’s user agent and change it frequently.

Make the crawling slower 

Based on browsing speed and the number of requests, websites can easily distinguish between a bot and human activity. When you bombard websites with requests simultaneously, the website will find your activities suspicious and detect the web crawler. You can schedule your bot to run at certain intervals to avoid this issue.

Further reading

• Web Scraping Tools: Data-driven Benchmarking
• Web Scraping vs Data Mining: Why the Confusion?
• The Ultimate Guide to Proxy vs. VPN: Which One Is Better?

For guidance to choose the right tool, check out data-driven list of web scrapers, and reach out to us: