Web scraping refers to the process of extracting data from a website using software designed to harvest information at scale.
During this automated process, unstructured data is scanned and copied from web pages, then converted into a structured data set and exported into a spreadsheet or database. This way, the retrieved data is presented in a usable format compatible with various applications for further analysis, storage or manipulation.
What Is Web Scraping?
Web scraping is an automated process that extracts mass amounts of data from a website using a software program.
Web scraping is used by companies because it provides a competitive edge. Collected data generates client leads, trend analysis, market research and price intelligence, Giedrius Karanda, a web scraping engineer at Legalist and founder of TechKaranda, told Built In.
“Think of it as a superpower that lets us gather vast amounts of information quickly, turning that data into potential customers or backing up strategic decisions.”
How Does Web Scraping Work?
Web scraping can be broken down into four steps. Hrvoje Jerkovic, principal data engineer and data consultant at Intuita Consulting, explains the process:
1. First, a web scraper inputs the URL (or URLs) of the web page being accessed, mimicking a regular user’s behavior, which loads the HTML code and establishes a connection. More advanced web scrapers are equipped to scan, or “crawl,” entire websites, including CSS and Javascript elements.
2. Once the server receives the HTTP request, an HTML code is sent back. That includes the raw text that defines the structure and content of a webpage.
3. At this point, a web scraper can begin to extract the specific data it’s programmed to find. For this, it relies on a method known as parsing, where a software program sifts through compiled data and identifies patterned information as it executes an encoded function.
4. Lastly, the targeted data is then exported into a structured format useful to the user, like a CSV file or Excel spreadsheet, for storage and further analysis. Other options include keeping the information in a database or transforming it into a JSON file for an API.
“The choice of format depends on the intended use of the data and the tools that will be used to analyze or process it,” Jerkovic said. “This is how scraped data becomes accessible and usable, turning it from raw HTML into a structured dataset that can be analyzed, shared or integrated into other systems.”
What Is a Web Scraping Tool?
A web scraper is a software tool programmed to extract mass amounts of information from a website. In short, it’s a specialized bot.
“Imagine a web scraping tool as a digital helper,” Karanda said. “It visits websites, ‘reads’ the information you’re interested in and then organizes the data for you in structured format.”
Web scrapers come in different builds, depending on what type of data its data selectors are coded to harvest from an HTML file. Factors like a website’s complexity, the type of data being mined and preferred storage format are all built into a web scraping tool, Jerkovic explained.
“Understanding the different types of tools and their applications can help in selecting the best approach for a given web scraping project,” he added.
This ranges from managing small-scale tasks that can be handled with a browser extension, large-scale projects that require a dedicated hosted service or custom-built solutions, which may use a framework like Scrapy.
Some other examples of web scrapers include Beautiful Soup, JSoup, Selenium, Playwright and Puppeteer, to name a few.
Types of Web Scrapers
To ensure web scrapers are effective, applying the correct type of web scraper for the job is crucial. Below are the most common kinds of web scrapers suited for different purposes.
Self-Built Web Scrapers
Those with advanced programming skills may feel comfortable enough to build their own web scrapers. While this path provides extra flexibility, those without in-depth coding knowledge may prefer other web scrapers.
Browser Extensions
Browser extensions are programs that can be added to a web browser as a plugin. These web scrapers are easy to install and require less work to operate, but they only scrape websites one page at a time. As a result, they’re best used for collecting smaller samples of data.
Web Scraping Software
Web scraping software needs to be downloaded onto a computer. It typically comes with more advanced features, like JavaScript and anti-bot solutions, and has less limitations than a web browser.
Cloud Web Scrapers
Cloud web scrapers run on off-site servers, and users don’t have to install any software. Cloud web scrapers can be more expensive, but they also offer powerful features, like IP rotation and API storage formats, and are capable of processing large amounts of data.
Rules for Web Scraping
There’s a sort of etiquette when it comes to web scraping. According to experts, these are the best practices for ethically gathering data:
Respect a Website’s Text File
A website’s text file — the string of alphanumeric, electronic text representing a stored web page — includes a robot exclusion protocol, coded as “robots.txt.” It instructs web scraping bots and search engine “crawlers” what can and can’t be accessed on a web page, and serves as the technical location of a website’s acceptable use policy.
“[Even though] this is the standard for all web pages, it still relies on voluntary compliance from crawlers and users,” Greg Hatcher, information security engineer and founder of offensive cyber security consultancy White Knight Labs, told Built In.
Professionals routinely check for this protocol before web scraping, which should be respected at all times.
Limit Rate and Volume of Requests
When a user visits a website, a request is sent to the server to deliver a web page, and that takes up resources like CPU, memory and bandwidth. So making sure a web-scraping bot doesn’t overload the website it’s trying to source from — by flooding its server with concurrent requests — is essential to ethical web scraping. You don’t want to disrupt the experience for other users or get banned.
Some strategies for limiting a program’s rate and volume include distributing requests evenly over time, programming staggered breaks in between requests or executing a data acquisition plan over a scheduled period of time to avoid detection.
“Reasonable scraping rates will help a user avoid being mistaken for a malicious bot,” Hatcher said.
Be Mindful of Regulations
Where you are geographically plays a role in your web scraping practice. For example, companies in the European Union are subject to GDPR compliance, regardless of its target audience’s location. And if a company operates outside of the EU but does business within EU borders or targets those living in the EU, the GDPR would still apply.
Exceptions to the matter include use cases that would pass legitimate interest, vital interest or public interest tests when challenged. One example being the Thorn project, which leverages technology and web scraping techniques to combat online sex trafficking. Although personal data is collected in the process, it identifies an average of nine victims per day while saving 60 percent of daily critical search time, according to its website.
Think Before Use
Scraping data from a website is one action. Posting or publishing the duplicate content is another. The latter is not considered ethical or, in some cases, legal. Duplicate content confuses search engines, leading to poor SEO ranking and penalties, and may be subject to copyright law.
Ask Permission
When in doubt, reach out. Karanda, who primarily uses web scraping for data analysis, pursuing prospective clients and analyzing price changes on competitor websites, said that if necessary, “we’ll reach out to website owners for permission to scrape their website.” It’s advisable to avoid scraping any information of a personal or sensitive nature unless given explicit consent, he added.
What Is Web Scraping Used For?
Mass data collection is one of the most powerful tools in the information age. When applied, web scraping proves to be an asset for the following use cases:
Market Research
Companies in every industry scrape websites, building massive databases in the process, to stay competitive. These industry insights are formed around data that analyzes everything from product performance and price tracking to customer reviews and competitor details.
Lead Generation
Online directories, job listings, email lists and social media profiles are all prime, web-scrape-ready targets for sales teams to build contacts and expand their client base.
SEO Monitoring
SEO monitoring tracks a website’s search engine rankings in order to form actionable insights on how to optimize this score. Web scraping can rapidly identify keywords and categories that may improve a piece of content’s SEO performance.
Price Comparison
Entire websites, browser extensions and applications have been developed to scrape pricing information across multiple e-commerce vendors in order to provide aggregate pricing information in real-time.
Amazon, for example, leverages big data analytics in its pricing structure. It makes over 250 million price changes every day, according to research by Omnia Retail.
Real Estate
Online property listings make it easy for real estate agents to collect the latest, most up-to-date information on vacancies in their areas. APIs can be built to auto-generate multiple listing service posts onto a company’s website, treating it as their own.
Social Media Analysis
Web scraping social media activity can inform brands of their customer reception. By seeking out specific keywords or hashtags, a company can better understand the status of their impact — positive or negative — based on what’s trending.
Is Web Scraping Legal?
Web scraping, in itself, is perfectly legal. The general rule is that all publicly available data on the internet is fair game.
That said, here’s what not to web scrape:
- Personal data
- Health records
- Financial information
- Intellectual property
- Data protected by a website’s terms of service agreement
- Data protected by international regulations
Web scraping is loosely regulated and can be weaponized by bad actors online to build counterfeit websites or steal competitive information. It can also damage a website if done aggressively or excessively, overloading the server with requests to the point of a crash, similar to a DDoS attack. This is why some websites, like Google and Amazon for instance, restrict web scraping in their terms of service.
Personal data, intellectual property, confidential information and data protected by copyright laws, use policies and international regulations — which vary by country — are off limits. The Computer Fraud and Abuse Act applies to usage in the United States whereas the General Data Protection Regulation defines these guidelines in the European Union. On a more localized scale, California has even implemented its own personal data protections under the California Consumer Privacy Act, enacted in 2018.
A recent example of illegal web scraping: When the University of California San Diego’s third-party business associate, Solv Health, installed Google Analytics on the hospital’s scheduling websites — without asking permission.
“The patient information that was scraped and sent back to Google included first and last names, email addresses, IP addresses, cookies and reasons for appointments,” Hatcher said. “This is a direct violation of those patient’s HIPAA rights.”
If any personal information is published by the user themselves, however, that’s a different story. As decided in a 2022 court ruling, HiQ Labs vs. LinkedIn, that personal information could be scraped if the information was made publicly available by the person.
The growing interest in data governance and malicious activity is said to put web scraping’s reputation in a sort of gray area. Yet everyday business is conducted with the same tools in an ethical, law-abiding way.
When it comes to web scraping, it’s more about how it’s being used.
Frequently Asked Questions
What is web scraping used for?
Web scraping is used for conducting market research, providing sales teams with leads and gathering real estate info on local properties, among other applications.
What is an example of web scraping?
Companies rely on ready-made or customized web scraping solutions to generate leads and expand their client base by lifting data from websites like Yelp, Google Maps and Amazon.
Can you get banned for web scraping?
Yes; if done irresponsibly, websites have built-in coding to detect bot-like behavior and protect its server from crashing.
