If you ever wanted to gather and extract valuable data from the web, writing a web crawler might be the best way to do it. Crawlers are data fetchers that can find, browse, and navigate websites to capture, scrape, extract and store the information you need.
They are programs developed to read data from the internet by locating and downloading the targeted web pages. Because of that, you can use them for various applications, such as scraping for competitor pricing from e-commerce websites, gathering user reviews and comments from social media, sports scores, stocks, financial information, etc.
Even though it’s much easier to script a web crawler today due to having the best programming languages with massive libraries, it still requires some know-how. Let’s talk about what a web crawler is and how to set up a crawling bot to build a database that you can rely on.
Basics of web crawlers
What is a web crawler exactly?
Put simply – it’s a program, an internet bot that browses and indexes data (content) of web pages on the web. Also called a crawling bot, spider, or robot, a crawler uses the power of automation to target, browse, and extract data and information from web pages. It also exports the extracted data into a series of structured formats, such as a database, table, list, etc.
The most popular internet bot every internet user knows about is Google. It is a search engine that uses its crawling bots to constantly search the web, looking for the freshest, most up-to-date content.
Without its crawlers, internet users wouldn’t be able to receive search results in mere seconds each time they request to see some online content. Billions of internet users generate quintillions of bytes of data daily. Imagine going through all that data without being able to automatically find what you’re looking for. Oxylabs has a blog which discusses the topic of “what is a web crawler” in more depth, you should definitely check it out.
Crawler scripting explained
Since it’s impossible to make sense of the internet without web crawling, a search engine is needed to quickly crawl the web, find and index the most relevant websites, and provide you with a web page you requested to see. You can build a web crawler to help you achieve all these goals and more.
In the digital business landscape, modern businesses use web crawlers for various purposes, including:
- Data aggregation– businesses need the latest data to fuel their operations, beat competitors, and find the best ways to increase sales. Web crawlers allow them to compile data on various subjects from an array of online resources and store it in one easily accessible and secure place.
- Sentiment analysis– knowing what the target audience thinks about particular products and services can help a business improve its marketing and advertising campaigns. Gathering feedback is also an excellent way to enhance your business strategy. A web crawler can collect valuable information regarding comments and reviews for analysis.
- Lead generation– finding as many sales leads as possible is the only way to stay relevant in the digital business landscape. Web crawlers can gather all the information a business needs to generate more leads. They can fetch contact information from attendee lists, public profiles, phone numbers, emails, etc.
The crawler scripting process allows users to determine what they want a crawler to do. Aside from the three use cases we mentioned here; you can use bots for lots of other applications as well.
The process of building a web crawler
Let’s see what it takes to build a web crawler.
Get ahead of coding to write your crawling script
Learning one or two programming languages is an excellent way to build a scraper that will do whatever you want it to do. Python is one of the most popular computer languages for writing bot code.
Python is mostly used for web scraping. It can send HTTP requests to multiple web pages and return the content of the targeted web pages. It also allows for better control and navigation through the pages to get the data.
Use web scraping tools
If coding is not an option, you can use web scraping tools to build a web crawler, such as Octoparse. A web scraping tool allows you to build a crawler that can extract the specific type of data you’re after. Simply run the program and locate the main menu.
Select Advanced Mode and enter the target URL to start the crawling operation. Set up pagination to help your bot discover the target web pages by clicking the Next Page button and opening the Tips Panel. Select the “Loop click single element” button, then select one item and click on it.
Go to the Action Tips Panel and select “Loop click each element” to allow your crawler to select all items with similar elements. Select “Extract the text of the selected element” and repeat as many times as necessary until you receive the information you need. Once finished, click Start Extraction.
Conclusion
Writing a script for a web crawler might sound like a tedious and time-consuming process. However, you have a wide range of tools and means you can use to get the job done at almost no maintenance or any other cost.
Just keep in mind that your crawler will need constant updates to cope with the ever-changing nature of web pages on the internet. Each website is unique and requires you to write a particular script that will be compatible with the site’s language. It takes a bit of time to get into the science behind it, but it’s quite manageable.