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How are Data Crawlers Made

Data crawling is not a new term in business. It is often used interchangeably with data scraping, although the two terms refer to two different processes.

Data crawlers, which are commonly referred to as web crawlers, spider bots, or bots, are tools that are widely used by search engines to index the web. It is through web crawling that users can receive relevant URLs that respond to their search query.

How Do Web Crawlers Work

A web crawler works with an initial list of known URLs, and from these websites, it is able to find new web pages. It also follows the URLs in the new web pages to find more content. The process continues until the crawler encounters an error or gets to a page that has no hyperlinks. 

Crawlers try to understand the content on these web pages by looking at the meta tags, image descriptions, and the site’s copy.

For each URL analyzed, the crawler uses a Fetcher to download the content on the page, and a Link Extractor that extracts the links on the page.

The links are filtered to find the most useful. The URL-seen module also checks the links to confirm if the crawler has already visited these pages or not. If they have not been visited, the Fetcher retrieves its content. Again, the link extractor gets any links in this new content. It filters and checks the links for duplication, and the process goes on.

In case a user makes a search query, the search engine assesses the indexed content. It then finds the relevant web pages, and arranges these pages from the content that answers the query best, to the least relevant.

How You Can Use Data Crawling For Business

1) Optimizing Your Site for Better Ranking

When a web crawler discovers new content on your site when crawling and lists your site on search engines, it increases the chances of potential customers finding your brand and making a purchase.

But you need to beat your competitors by ensuring that you rank high on the SERP.

You can achieve this by using a web crawler to view your site the way a crawler sees it. You can then fix broken links, correct errors, optimize your meta tags, and include relevant keywords.

2) Data Scraping

A web crawler can also help in data scraping. Data scraping is the automated process of extracting data from targeted websites and storing this data in a spreadsheet or database for further analysis.

Data scraping helps with market research and decision making. 

The crawler can help in finding websites that are relevant to your web scraping project and downloading these sites. You can then use the scraper to extract the needed data. 

How Do You Geta Data Crawler?

The easiest way to access a web crawler is by paying for a subscription from the numerous vendors in the market. But you can also use a programming language to write the code. 

1) Building a Crawler Using Python

Python is a commonly used language. We will use it to illustrate how to build your crawler. You will need to make use of the scrapy package that comes with Python. 

Here is the basic code.


class spider1(scrapy.Spider):

name = ‘Forbes’

start_urls = [‘’]    

def parse(self, response):


This code comes with three main components:

  1. a) Name 

This is to identify the name of the bot. In our case, we are using Forbes. 

  1. b) Start URLs

These are the seed URLs. They give the crawler a starting point. In the code above, the URL belongs to a Forbes page on clustering algorithms. 

  1. c) A parse()

This is the method that you will use to process and extract the necessary content from the page. 

2) Buying a Ready-made Crawler

Like we mentioned, you can make things easier by getting a ready crawler. They are commonly built with programming languages such as Java, PHP, and Node. 

Here are a few things you should keep in mind when getting the crawler

  1. a) Speed of the bot

The crawler should be fast enough to crawl the web pages within your time constraints.

  1. b) Accuracy

You need an accurate crawler. For instance, it should stick to the rel=”nofollow” you have set by not following the specified pages.

  1. c) Scalability

The crawler should be capable of growing with the growing needs of your business. You should have the option to crawl more websites without having to invest in more tools. One of the best crawlers on the market is sold by Oxylabs, but you have many different options.

Winding Up

Most people associate data crawling with search engines, but this does not mean that your business cannot benefit from investing in one. A data crawler will make your data scraping project easier by indexing the web pages containing the information you need. All you need to do is extract the content you need for your research from the downloaded pages.

There two ways to get a crawler – build or buy. Buying is the best option for those without coding experience. Ensure that your vendor is reputable and that the crawler is quick, accurate, and scalable. 

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What do you think?

Kane Dane

Written by Kane Dane

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