Web crawling technology is instrumental in the ever-expanding digital universe of 2023.
As the web keeps growing, these crawlers are working harder than ever.
Although it might seem like just another tech term, it has a unique and vital function.
In this blog, we’ll answer – What is a web crawler and how does it work, uncovering its secrets and understanding its significance.
What is a web crawler, and how does it work?
A web crawler is a computer program that automatically and systematically browses the internet to collect information about websites and their pages.
Think of it as a “robot” that visits websites, reads their content, and then follows links to other pages, continuously repeating this process. Search engines like Google use web crawlers to gather data so they can provide accurate search results.
These crawlers play a pivotal role in how search engines work. When you type something into a search bar, the results you see are based on the information these crawlers have collected. They help search engines quickly present relevant information in response to your queries.
Types of Web Crawlers
Now that you understand what a Web Crawler is, it is time to learn about the types of web crawlers. Here are 4 of them:
1. General-purpose Crawlers
Often referred to as the internet’s explorers, general-purpose crawlers have a vast territory to cover. Their mission takes them to various corners of the web, collecting information from a myriad of sites. Renowned search engines, such as Google and Bing, heavily depend on these crawlers. Their task is to compile an exhaustive directory of the ever-growing world of websites.
2. Focused Crawlers
Unlike their more general counterparts, focused crawlers have a clear mission in mind. They aren’t the wanderers of the web; instead, they zero in on designated websites or specific subjects. When researchers and advertisers are on the quest for detailed insights about a niche topic or a particular website, it’s the focused crawlers they turn to.
3. Incremental Crawlers
Consistently seeking what’s new, incremental crawlers are the internet’s vigilant overseers. With a routine of frequent visits, they’re on a perpetual watch for fresh additions or modifications on websites. Their diligent work plays a pivotal role, helping giants like Google maintain up-to-date and pertinent directories of the ever-evolving web landscape.
4. Deep Web Crawlers
Journeying into the lesser-seen regions of the internet, deep web crawlers have a unique task. They navigate the vast expanse of the deep web, where typical search engines don’t venture. These areas are full of web pages not listed or indexed by standard search engines. As a result, researchers turn to these crawlers when they’re on the hunt for elusive information that isn’t readily available to the public.
If you are interested, learn about web scraping types.
How Web Crawlers Work: A Step-by-Step Explanation
As we have learned, Google, Bing, or DuckDuckGo find and organize all this data to present relevant results in mere seconds with the he. Here is how Web Crawlers work:

Step 1: Starting Point
Every journey begins somewhere, and for web crawlers, it starts with a seed. Seeds are essentially lists of known URLs. These crawlers don’t blindly wander the vastness of the internet; they begin by inspecting these seeds. Examining these URLs, they begin their web exploration, laying the foundation for their extensive journey.
Step 2: Discovery Process
The internet is a vast web of interconnected information, and hyperlinks are the bridges that connect these islands of data. As web crawlers navigate a webpage, they identify these hyperlinks, which point to other URLs. But it’s not a haphazard journey.
Several policies influence the route a crawler chooses to follow. Factors such as the number of links to a page, page views, and brand authority can determine its importance, making some paths more attractive than others.
Step 3: Content Analysis
When a crawler lands on a webpage, it doesn’t just glance over it. It meticulously examines the content, storing vital data and meta tags – the descriptive labels about the page’s content. This information helps search engines determine when and where to showcase a webpage in response to a user’s query. It’s like reading a book and highlighting the important parts for future reference.
Step 4: Storing the Data
Once the crawler captures the necessary information, it’s time to organize and store it. This process, known as search indexing, is analogous to cataloging in a library. The aim is to efficiently store data so that when a user searches for specific information, the search engine knows where to find and retrieve it.
Just as a library has an index to guide readers to the right book, search engines use indexing to point users to the most relevant web pages.
Step 5: Respecting Robots.txt
Web crawlers operate on a principle of respect. Before accessing and indexing a site, they consult the website’s robots.txt file. Think of this file as the website’s rulebook, outlining which pages a bot can access and which links it can follow. Adhering to these guidelines ensures that crawlers only access content they’re permitted to view.
Step 6: Dealing with Duplicates
The internet, vast as it is, often has repetitive information. Web crawlers are designed to recognize and sidestep duplicate content. Their goal is to index unique and valuable content, ensuring users are provided with the best and most relevant search results.
Step 7: Frequency of Crawling
The digital landscape is ever-changing. Webpages get updated, content is revised, and new information is constantly added. Recognizing this dynamic nature, web crawlers don’t just visit a site once and forget about it.
Web Crawlers routinely revisit webpages, ensuring that their stored data remains updated and relevant to current times.

What are web crawler tools?
Web crawler tools are specialized software applications designed to browse the internet and collect data from web pages. They play a crucial role in various sectors, from market research to SEO strategies. Here are some of the prominent web crawler tools available:
1. Octoparse

Recognized as one of the best web crawlers, Octoparse allows users to extract web data directly into spreadsheets. Tailored for those without coding experience, it offers features such as:
- Scheduled cloud extraction for real-time dynamic data.
- Auto-detect mode for automatic data scraping.
- Preset templates for popular websites like eBay and Amazon.
- Bypass mechanisms to circumvent ReCaptcha and blocks.
- Data cleaning functionalities using Regex and XPath.
2. 80legs

A powerful and customizable web crawling tool, 80legs supports the collection of vast amounts of data. Its notable features include:
- API for creating crawlers and managing data.
- Scraper customization using a JS-based app framework.
- A suite of IP addresses for web scraping requests.
3. ParseHub

Designed to handle complex data collection tasks, ParseHub can extract data even from websites using AJAX, JavaScript, and cookies. Its capabilities encompass:
- Integration with platforms like Google Sheets and Tableau.
- Data export in formats such as JSON and CSV.
- Compatibility with devices running Mac, Windows, and Linux.
4. Visual Scraper
Apart from its Software as a Service (SaaS) offering, Visual Scraper provides data delivery services and bespoke software extractors. It allows users to schedule and automate data extraction tasks. Key features include:
- Support for data formats like Excel, CSV, MS Access, and more.
- A note of caution: The official website might not be frequently updated.
5. WebHarvy

WebHarvy is a point-and-click web scraping software designed for users without programming skills. Its functionalities are:
- Capability to scrape text, images, URLs, and emails from websites.
- Proxy support for anonymous data extraction.
- Multiple data export formats, including XML, CSV, JSON, and TSV.
How Web Crawling Can Benefit Your Business?
Web crawling is a powerful tool that can offer numerous advantages to enterprises, big or small. Here’s how web crawling can significantly benefit your business:

1. Monitoring News and Social Media
Staying updated about what the world is saying about your brand is crucial. Whether news articles or tweets, web crawlers can scan various platforms like news sites, social media channels, and industry forums. By doing so, they offer insights into public sentiment about your brand and competitors. Such data can empower your marketing team, enabling them to gauge the company’s image and understand customer perceptions.
2. Gaining Competitive Insights
Knowledge about competitors is invaluable. Instead of manually browsing competitor sites to discover their latest offerings, pricing strategies, or promotional campaigns, web crawlers can automatically fetch this information. This saves time and ensures you’re always a step ahead in the competitive game.
3. Boosting Lead Generation
For many businesses, leads drive revenue. Web crawlers can expedite the process by extracting data from various sites that influence your revenue streams. For instance, staffing agencies can leverage crawlers to identify companies with hiring needs, allowing them to pitch their services proactively.
4. Creating Target Lists Efficiently
Web crawlers can be programmed for entity extraction, making the process of creating targeted lists effortless. For example, if a car association wants to connect with all dealerships and manufacturers, crawlers can retrieve relevant details like addresses, contact names, and phone numbers, consolidating them into a single, accessible database.
5. Instant Posting Alerts
Web crawlers can be a game-changer for businesses that rely on timely information, like real estate agents scouting for properties. They can be set to track specific sites, sending alerts for new listings that match predefined criteria. This ensures that you’re always the first to know, giving you a competitive edge.
6. Streamlining Supplier Pricing and Availability Checks
Comparing offerings can be tedious if your business involves frequent purchases from multiple suppliers. Web crawlers can automate this task, fetching details about product availability, pricing, and more from various suppliers. This saves time and ensures you’re always getting the best deals.

Examples of Web Crawlers
Many of today’s leading search engines employ unique web crawlers, each equipped with specialized algorithms to extract details from web pages. Depending on their design, these crawler tools can function on desktop systems or through cloud platforms. Here’s an overview of notable web crawlers associated with various search engines:
- Amazonbot: The digital spider behind Amazon’s search capabilities.
- Bingbot: Crafted by Microsoft, this tool powers Bing’s search inquiries.
- DuckDuckBot: The engine propelling the privacy-focused DuckDuckGo search platform.
- Googlebot: The backbone of Google’s extensive search ecosystem.
- Yahoo Slurp: Yahoo’s answer to web crawling needs.
- Yandex Bot: The muscle behind the searches on the Yandex platform.
Why are web crawlers called ‘spiders’?
The vast digital space that users typically navigate is termed the World Wide Web, denoted by the familiar “www” in website addresses. Drawing an analogy from nature, these search engine bots were aptly named “spiders.” Much like actual spiders traverse intricate webs, these digital spiders meander through the vast interconnected realm of the internet.
Web crawling vs Web scraping
So far, we have talked about web crawling only. Now we will learn about web scraping.
Web scraping is the automated process of pulling particular data from websites. Think of web crawling as sketching a broad outline of the internet, whereas web scraping is akin to zooming in on specific site details, such as product prices or weather forecasts. A web scraper focuses on designated sites and extracts the precise information of interest.
Here is a table outlining the differences between Web crawling vs Web scraping:
Parameter | Web Scraping | Web Crawling |
Primary Tools | Utilizes a Web Scraper. | Employs Web Crawlers or Spiders. |
Main Purpose | Focuses on downloading specific information from websites. | Aims at indexing web pages for search engines. |
Scope of Operation | Doesn’t necessarily explore all pages of a website; targets specific data. | Comprehensively visits every page, scanning every bit of content. |
Adherence to robots.txt | Typically, web scrapers might not obey the robots.txt file directives. | Not all web crawlers adhere to robots.txt, but many do, especially the ones from major search engines. |
Scale | Can operate on both small and vast scales, depending on the requirement. | Predominantly used on a large scale, especially by search engines. |
Applications | Find utility in areas like Retail Marketing, Equity Research, and Machine Learning. | Primarily powers search engines to provide relevant search results to users. |
Data De-duplication | De-duplication of data isn’t always a standard feature. | Integral to the process, ensuring unique data entries during indexing. |
Required Components | Needs both a crawl agent and a parser to interpret the fetched data. | Primarily requires just the crawl agent. |
Examples | Tools like ProWebScraper and Web Scraper.io are prominent examples. | Major search engines like Google, Yahoo, and Bing are classic examples of web crawling in action. |
If you want to know about data scraping and how it is compared to web scraping, click here.
Why is Core Devs Ltd. Your Premier Choice for Web Crawling Solutions?
In this digital epoch, the vast expanse of the web offers invaluable data. With CoreDevs, you not only navigate this expansive realm but also derive significant insights from it. Our comprehensive web crawling solutions are crafted to empower you with an edge in knowledge-driven decision-making. Let’s explore the unique strengths of each of our specialized solutions:
Website Crawling and Data Retrieval
Navigate and extract critical information from the vast web landscape to enhance your strategic decisions. Be it understanding digital market nuances, evaluating online competitors, or perceiving user behaviors, our crawling solutions ensure you have the necessary data to inform your strategies.
Advantages of This Solution
- Make decisions anchored in robust data.
- Swift and meticulous extraction from web sources.
- Ensure timely and accurate data accessibility.
Social Media Crawling
Delve deep into social media realms to extract insights, identify prevailing trends, and understand audience inclinations. Our proficient crawling techniques keep you synchronized with digital audiences, allowing for real-time strategy tweaks and optimizing data-driven engagement endeavors.
Advantages of This Solution
- Analyze the efficacy of competitive social media endeavors.
- Act promptly on digital trends and discussions.
- Amplify social media insights and strategic outreach.
Job Portal Crawling
Consolidate job offerings from a plethora of portals to supercharge your recruitment strategy and remain updated with the latest opportunities. We optimize your recruitment journey, ensuring a panoramic view of the talent landscape and promoting informed hiring decisions.
Advantages of This Solution
- Centralized access to diverse job portals.
- Rapid identification of potential candidates.
- Optimize your recruitment strategy.
Real Estate Web Crawling
Traverse the digital real estate space, extracting key data points, from property listings to market fluctuations, to reinforce your investment plans. Our solution ensures you’re armed with the latest and most accurate data, positioning you advantageously in the online real estate market.
Advantages of This Solution
- Forge well-informed real estate investment strategies.
- Seamless access to online property listings and market shifts.
- Act decisively on digital real estate opportunities.
News and Media Web Crawling
Stay updated by crawling through news and media sites, ensuring you’re always informed, can anticipate industry movements, and gather essential data. We keep you connected to the heartbeat of the media landscape, offering instantaneous insights to influence your decisions.
Advantages of This Solution
- Stay abreast of industry news and updates.
- Instantaneous understanding of media dynamics.
- Act swiftly to capitalize on emerging narratives.
Content Web Crawling and Curation
Search and curate content across the web, creating rich repositories tailored for specific audiences. Our solution delivers insights, resources, and data, setting the stage for impactful audience engagement.
Advantages of This Solution
- Curate bespoke content repositories for niche audiences.
- Efficient web-based content discovery and curation.
- Cement your authority and credibility in the digital space.
With Core Devs at your side, our Web Crawling Solutions transcend mere data retrieval, converting web data into actionable insights. Elevate your digital strategies, gain a competitive edge, and propel your business forward with the expertise of Core Devs!

Final Word
The realm of the internet is vast and continually evolving, but understanding its intricate web becomes simpler when you know the key players. Through this blog, you’ve gained insights into What is a web crawler and how does it work?
As you navigate the digital landscape, be equipped with this knowledge. Remember, every search result you see is a testament to these diligent digital spiders. Happy browsing!