Web Crawler vs Web Scraper: What’s the Difference and How They Work Together

In this web crawler vs. web scraper article, we discuss the key differences between these tools and how they are used together in data scraping projects. This guide includes detailed explanations of how they work, why you need them, the key differences in their roles, and more. Without wasting any more time, let’s get started with this web crawling vs web scraping comparison.

Key takeaways

• Web crawlers and scrapers play different roles: Crawlers discover web pages and scrapers extract specific data from those pages to help build a database of useful information. 
• Scraping has many business uses: Price tracking, lead generation, SEO research, market analysis, and powering AI tools.
• Scaling scraping has challenges: Anti-bot systems, scheduling, maintaining data quality, and compliance. 
• Crawling is essential for SEO: Search engines rely on crawlers to find and index your pages, so improving crawlability helps your site rank better.

What Is Web Crawling?

Web crawling is an automated process for discovering and scanning web pages of different websites on the internet. A web crawler is used to execute this process. It crawls through links from one page to another, collecting crucial details about each page visited. The main goal of the crawler is to understand the map and structure of a website. 

Search engines such as Google use crawlers to discover webpages on the internet. Their crawlers visit different websites on the internet, scan these pages, and store the important information in their database.

How Does a Web Crawler Work?

A crawler starts with a list of URLs known as seed URLs. It then visits each of these pages, scans the content, and then follows any internal or external links it finds. So, if a crawler visits a homepage of a website, it will move to other pages using the links from the homepage. That’s why internal linking is one of the most recommended SEO practices.

To avoid overloading a single website, crawlers use scheduling logic to decide which pages to visit first and how often to return to them.

Example of a Web Crawler in SEO

As stated earlier, search engines like Google and Bing use crawlers to continuously scan websites to discover new pages and updates. After scanning the web pages, these crawlers send the data to the search engine’s index, where pages are analyzed and ranked based on relevance. Without these crawlers Google would not know what content is on each webpage and how it is related to the rest of the content on a given website. 

What Is Web Scraping?

Web scraping is the process of extracting structured data from webpages of a given website or web application. Instead of manually copying and pasting data from a web page, scrappers collect it automatically by turning unstructured web content into usable formats like CSV, JSON, or database entries. When data is structured, it is much easier and efficient to analyze. 

How Does a Web Scraper Work?

A web scraper starts by sending a HTTP request to the target webpage and then downloads the discovered HTML content. It then parses data in the HTML looking for important information such as prices of goods and any other details it is configured to look for. After extracting the targeted information, the scraper stores it in a structured format for further analysis or automation. 

Modern scrappers are also designed to handle JavaScript-rendered pages by using headless browsers. This allows them to scrap data from modern websites that do include a lot of Javascript elements. 

Why Do I Need a Web Scraper?

There are several real world use cases for web scrapers. Some of the common reasons for scraping data from targeted websites include:  

• Price monitoring: Scraping helps users such as businesses or researchers track competitor prices or market trends.
• Lead generation: By using scraping tools, businesses can collect useful information about their prospects, including emails, business contacts, or company details.
• Market analysis: Businesses scrape data to study trends across industries or products.
• SEO research: Scrapping also gathers information about keywords, backlinks, or content data to help shape the SEO strategy of the business.
• Academic or data research: Researchers rely on web scraping to extract information for studies or reports.

Types of Web Scrapers

There are several types of web scrapers that you can choose based on the task at hand and your priorities. Some of the common types include: 

• Manual scrapers: This method involves simple copy-and-paste or browser extensions for small tasks. For instance, you can visit a web page on Amazon and copy all the information about a specific product.
• Automated scrapers: With this method, scripts or tools used to collect and process large amounts of data from various websites. 
• API-based scrapers: This method involves using official APIs provided by various platforms to fetch data directly when available.
• Headless browser scrapers: Using this method involves simulating a real browser to scrape sites that rely on JavaScript or dynamic content.

Crawler vs Scraper: Key Differences

Here is a summary of how web scrappers and crawlers differ.

Feature	Web Crawler	Web Scraper
Purpose	Discovering, navigating web pages, and collecting urls	Extract specific data from web pages, focusing on only what matters
Main Input	Seed URLs or starting points	URLs provided manually or by a crawler
Main Output	List of discovered URLs	Structured data (CSV, JSON, database entries)
Scope	Broad exploration of entire sites or the wider web	Extracts specific data from selected pages
Operation Style	Follows links automatically and maps site structure	Parses HTML and extracts targeted content
Typical Use Cases	SEO indexing, site audits, large-scale discovery	Price tracking, lead generation, research, automation
Dependency	Works independently but often provides links for scrapers	Often relies on crawlers to supply URLs for extraction

How Web Crawling and Web Scraping Work Together

Now that we know the differences between scrappers and crawlers, let’s explore how these two tools can be used together. 

Businesses often use web crawling and web scraping together to collect data. The crawler’s job is to discover and gather all the relevant pages on a website. After the pages are found, the scraper visits each one, processes the content, and extracts the specific data it was configured to collect. Using both tools together automates page discovery and data extraction, making the whole workflow faster and more efficient.

How Web Scraping Fuels Your Business

Web scraping provides businesses with valuable insights that can help them make more data-driven decisions. By using scrappers, business can: 

• Monitor competitor prices to inform their pricing strategy
• Track market trends to determine the best products to offer and at what time
• Collect data to train AI algorithms that they can use in tools like support chatbots. 
• Save time since manual data collection takes a lot of time. 

Overall, scraping is a crucial part of research for businesses that intend to make decisions based on real market data and not assumptions. 

Data Scraping for Business

Data scraping has become an essential part for business in several industries, including finance, health, technology, and more. Let’s explore some of the real world applications to learn more how data scraping is used there: 

• In eCommerce: Businesses use scraping to collect data about competitor prices, product availability, and customer reviews. 
• In finance: Business in the finance sector using data scraping to gather market data, news updates, and investment insights. 
• SEO Monitoring: Digital markets and business rely on scraping to analyze targeted keywords, backlinks, and competitor content. 
• Data Analytics: Data analytics tools need to be fed a lot of data to effectively generate reliable insights. The quality of insights largely depend on the quality and quantity of data and scraping can help with both of these. 

Web Scraping at Scale: Practice and Theory

Web scraping in theory looks simple and straightforward. However, the actual data collection process has several challenges that you need to be aware of. Some of these challenges include: 

• Ant-bot Systems: Websites often use anti-bot tools such as CAPTCHAs, IP rate limits, and bot-detection systems to block scrapers. To overcome this challenge, scrapers need to use rotating proxies that offer rotating IPs, so when one IP is blocked, the connection can be maintained using a new IP. 
• Scheduling: In data scraping, scheduling your workloads is crucial. You need to schedule the requests to avoid overwhelming websites. This may include sending requests during off peak hours. 
• Data quality: As stated earlier, the quality of the data collected has a huge impact on the overall outcome, especially if you need to use the data to make crucial business decisions. That’s why scrapers need proper validation and cleaning steps.
• Compliance: When implementing large-scale scraping, you must follow legal and ethical rules, respecting robots.txt instructions and data privacy requirements.

Web Crawling and SEO Significance

If you own a website or web application that you need to be visible in search results on platforms like Google, it is important to make your webpage crawlable. If crawlers from search engines find it hard to crawl your webpages, they may not appear in search results.

To improve crawlability, site owners need to:

• Create XML sitemaps
• Build strong internal linking
• Ensure their robots.txt file does not block important pages. 
• Have clean URLs
• Ensure fast loading times for all pages
• Avoid duplicate contents

Conclusion

Web crawlers and scrapers are important tools that can be used together to improve the effectiveness of the data collection process. Crawlers discover web pages, and scrapers collect the important data on those pages. Crawling and scraping are crucial parts of the data collection process, especially for businesses that rely on data to make important decisions.

If you are a website owner, you may also want to make your site easier to crawl to increase the chances of your pages appearing in search engine results for relevant queries. In summary, web crawlers and scrapers are different tools, but when used together, they make data collection far more efficient. 

FAQs

What is the main difference between a crawler and scraper?

The main role of a crawler is to discover webpages and their URLs, which are then saved in a database. On the other hand, scrapers are used to extract specific information from webpages. So, scrapers discover URLs and send them to scraper to handle the data extraction. 

Can web scraping work without crawling?

Yes, scraping can be done without crawling as long as you know extra URLs you intend to extra data from. The main role of crawling is to discover URLs. 

Is web scraping legal?

Yes, web scraping is legal, but it has to be done ethically. Businesses and individuals scraping data need to follow the terms of the target websites and also remember to respect copyright laws when using the collected data.

What tools are best for crawling and scraping?

Some of the tools that can handle both crawling and scraping include Scrapy, BeautifulSoup + Requests, and Playwright. If you’re searching for two-in-one tools, these are some of the best choices available. 

How do search engines use web crawlers?

Search engines use web crawlers to find new content on the internet. The crawlers visit websites, follow links, and map out the structure of each site. They then store all the found URLs in an index. This indexed content is what search engines use to rank results for a given query based on relevance.