What Is a Web Crawler? How Web Crawlers Work, Types, and Business Use Cases

The main issues of web scraping are web data quality and speed. Search engine scraping and extracting data from e-commerce websites at scale requires high-speed crawlers that do not compromise the quality of extracted data.

A powerful web crawler that both crawls and scrapes complicated targets, parses data, and ensures a high success rate without any maintenance, would be ideal for any business that prefers to make data-driven decisions.

But before we get to the solution, let’s have a better look at the concept of a web crawler. What is a web crawler and how does it work?

What is a web crawler?

A web crawler (also known as a crawling agent, a spider bot, web crawling software, website spider, or a search engine bot) is a tool for accessing websites and gathering information. In other words, if you intend to use a program or a bot to gather specific public data, a web crawler is the solution for you.

How does a web crawler work?

Web crawlers start from a list of known URLs and crawl these webpages first. The crawling process then continues as crawlers discover and access additional pages. What happens next?

Discovering new URLs through hyperlinks

After crawling the initial pages, web crawlers find hyperlinks to other URLs, and the next step is to crawl them. As a result, this process can be endless. Depending on the purpose of the crawl, focused web crawlers can be configured to discover specific pages rather than an entire website.

Following crawl rules

This is why web crawlers follow particular rules, such as deciding what pages to crawl, when they should crawl these pages again to check for web content updates, and much more.

Supporting web data collection

Furthermore, web crawler bots can be used by companies that need to gather data for their purposes. In this case, a web crawler is usually accompanied by a web scraper that downloads, or scrapes, the required information.

Managing web crawler speed

Another crucial aspect to consider is web crawler speed. If your requirements are high and you need to crawl, for example, hundreds of thousands of pages, very few standard web crawlers can achieve this efficiently. Furthermore, crawling multiple threads at high speeds may overload the target website's server, negatively affecting both the website owner and your own projects.

Respecting robots.txt and ethical crawling

Therefore, ensuring your web crawling tools are used in an ethical manner should be a top priority. To help manage crawler behavior, websites can use a robots.txt file, which directs crawlers on which pages should be crawled and how frequently.

What a web crawler doesn't do

A web crawler is designed to discover webpages and URLs, but it does not extract structured data from webpages, parse page content, render complex JavaScript applications, clean or analyze collected data, or store information for reporting. These tasks require additional tools, such as web scrapers for data extraction, headless browsers for rendering dynamic websites, databases for storage, and analytics tools for processing the collected information.

Web crawling vs. web scraping

Note that the way web crawling works is not the same as web scraping, neither is the purpose of these processes. Web scraping aims to parse and extract data from a website, while web crawling is primarily focused on discovering target URLs. We have a dedicated crawler vs scraper blogpost discussing the topic in great detail, so if you're curious to learn more, check it out.

Types of crawlers

When discussing the various types of crawlers, there are usually three categories:

1. Desktop crawler. 

These crawlers mimic user behavior and are commonly run through computers or browsers installed on desktops. As a result, these crawlers can effectively make HTTP requests and gather the results easily.

2. API-Based Crawlers. 

The core feature of these web crawler bots is that they don’t crawl the pages themselves. The requests are instead sent to API endpoints, from whom the specific structured data is gathered.

3. Cloud-Based Crawlers.

A key feature of these crawlers is that their crawling workload is distributed across multiple machines or instances, allowing for increased scalability and performance. This makes cloud-based crawlers perfect for large-scale crawling tasks.

What is an example of a web crawler?

In general, most web crawlers are created for the work of search engines. Search engines use different web crawlers to index websites and deliver the right pages according to keywords and phrases. Every search engine uses its own web crawlers. Google, for example, uses Googlebot, which encompasses two types of web crawlers: Googlebot Desktop and Googlebot Smartphone. Notably, Google primarily indexes the mobile version of the web content, so the vast majority of Googlebot crawl requests are made using the mobile crawler.

Various providers offer web crawlers, like Screaming Frog, for companies that prefer to make data-driven decisions. For example, in e-commerce, there are specific web crawlers that are used to crawl information that includes product names, item prices, descriptions, reviews, and much more. Furthermore, web crawlers are used to discover the most relevant and gainful keywords from search engines and track their performance.

What is Oxylabs Web Crawler?

The web crawler tool is a feature of Oxylabs Web Scraper API for crawling any website, selecting useful web content, and having it delivered to you in bulk. With the help of this feature, you can discover all pages on a website and get the needed website data from them at scale and in real time. To check how our web crawler works in action, watch the video below.

E-Commerce Scraper API only charges for successful requests, ensuring fair pricing and reduced costs on your end. It is easy to integrate and requires zero maintenance from your side.

E-Commerce Scraper API reduces data acquisition costs. It replaces a costly process that requires proxy management, CAPTCHA handling, code updates, etc. 

Access accurate results from leading e-commerce websites based on geo-location. Oxylabs’ global proxy location network covers every country in the world, allowing you to get your hands on accurate geo-location-based data at scale.

Get all the data you need for your e-commerce business. Whether you are looking for data from search engines, product pages, offer listings, reviews, or anything related, E-Commerce Scraper API will help you get it all.

E-Commerce Scraper API has three integration methods: callback, real-time, and proxy endpoint. You can read more about each integration method in Web Scraper API Quick Start Guide.

Real scraper API use case

Many various e-commerce businesses choose Oxyabs’ E-Commerce Scraper API as an effective data gathering method and solution to data acquisition challenges. 

One of the UK’s leading clothing brands were looking for a solution to track their competitor’s prices online. Based on this data, they wanted to make more accurate pricing decisions that would lead to better competition and, essentially, more revenue. The company had an in-house data team, but overall costs for such complicated data extraction were too high and their resources were limited.

Oxylabs’ E-Commerce Scraper API (Web Scraper API) helped the company collect all required data, including product names, prices, categories, brands, images, etc. As a result, the company optimized their pricing strategy based on real-time data and increased online sales by 24% during the holiday shopping season (market average was 18%).

This company’s success story is just one of many ways Oxylabs’ E-Commerce Scraper API can help e-commerce businesses increase their performance.

Making the most of web crawlers

Web crawlers are an essential part of how search engines and businesses discover and collect website data at scale. They crawl pages, follow relevant links to discover new URLs, and can revisit existing pages to identify updates. Search engines use crawlers to discover and index pages, helping them organize content and deliver relevant search results on search engine results pages.

For businesses, web crawling supports a wide range of use cases, from competitor monitoring and data collection to search engine optimization and large-scale data extraction. Crawled website data can also be used to build training data for large language models and support other data-driven applications.

Effective web crawling requires more than simply accessing a web server, and understanding how crawlers work and how they differ from web scrapers can help businesses choose the right approach for their data collection needs.

Looking for the right tool for your project? Explore our guide to the best web crawlers and website crawling tools to compare available options.