Web Crawling vs. Web Scraping
Web scraping and web crawling are often used interchangeably. They’re both used for data mining, right?
Yes, but they are not the same thing. In this article we’ll look through the key differences between web scraping and web crawling as well as help you decide which one is relevant to you and your business.
In layman’s terms, web crawling is what search engines do: going through the web, looking for any information, clicking on every link available.
It’s quite a generic process with the goal of collecting as much information as possible (if not all) on the needed site. Basically, it's what Google is up to - view the page as a whole and then index all information available.
What is web scraping used for? Well, if you want to download the information gathered, you’d want to go for web scraping. Web scraping (sometimes referred to as web data extraction) is more of a targeted process.
You can tweak the commands and scrape very specific information from your target website using scraping proxies. You can then download the results in a relevant format (e.g. JSON, Excel).
There might be some cases where you’d want to use both web crawling and scraping to accomplish one goal, almost using them as step one and step two in your process. With both combined, you can get large sets of information from major websites using a crawler and then extract and download the specific data you need using a scraper later on.
What Software Should you Use?
Another big difference between the two is the software used. For web crawling tasks, you’d want to use a crawler, most of the time lovingly referred to as spider (or an automatic indexer if you have something against spiders).
As for scraping, there are plenty of different tools out there, referred to as scrapers. Which one you want to use depends on what your preferred scraping methods are.
If you're a beginner, we'd recommend going with ParseHub or Octoparse, if you prefer Python - try Scrapy or Beautiful Soup. And if you're more of a NodeJS kinda guy, look into Cheerio and Puppeteer. If you're feeling stuck, our support is here 24/7 just to answer any questions you might have.
Crawling vs Scraping: Examples
For you to pick whether you need to scrape or crawl, it would be useful to see what can be done with both of the methods. First, let’s take a look at an example how you can use data crawling to your advantage.
If you want to audit your own website, check for broken links and generally do some SEO guru magic, you might want to look into Screaming Frog, a SEO crawler. With the software crawling your website, it can detect 404 errors, analyse your Meta Data, find duplicates - all in all, collect all information possible.
By the way, detecting 404 errors is also used as a SEO trick to boost brand visibility. Finding broken links on other websites and informing their webmaster can help you place your own link instead. You can find more information about this method in our case study section.
As for web scraping, a popular use case example would be price intelligence research. Basically, if you wanted to sell a particular item on Amazon, you’d need to get some idea what the price range for similar products is. This is where you put a scraper to work (if you’re a beginner - you can’t go wrong with Octoparse). We won’t go into the nitty gritty of it in this article, but after your project is done, you’d end up having a list of items, URLs and their prices. Of course, you can expand or narrow the information you want to extract according to your needs. Pretty neat, isn’t it?
Another great example is ad verification. Residential proxies will help you test your ads, optimize CPA, and verify affiliate links. Localized ads are crucial when you're targeting foreign markets – and so are affiliate links. Keeping an eye on these will help you increase your sales and broaden your audience.
When your brand grows, so does your visibility, making it more vulnerable to fraud. Web scraping can help you protect your brand and its identity. There is a high likelihood that you will find your images or style reused by your competitors on their own websites. Besides this, other startups might even try to steal your idea and present it as their own. If you don't protect your brand from theft, you might have to start your business from scratch. Protect your ideas, as they make up the value of your trade.
Web crawling and web scraping are not niche subjects – they are often used by all kinds of businesses, starting from entrepreneurs, and ending with enterprises.
Frequently Asked Questions about Crawling and Scraping
What is the difference between web crawling and web scraping in short?
Web crawling gathers all the information available on the web, and web scraping gathers only specific information. A web crawler will find every line of text, image, and link there is, whereas a web scraper will find your targeted prices, links, and skip through anything that you're not looking for. These processes can go hand in hand when you use them both to maximize the outcome.
What is web crawling used for?
Web crawling is used to extract data – the crawler collects information that is on the page, and the pages that it leads to. This data can help websites keep up to date with what their competitors are doing, among other uses. If you want your website to appear on the first page of Google, you have to optimize it for the Google bot. The bot constantly crawls pages and indexes them. These pages are ranked based on many factors like the time it takes to load the page, and whether it doesn't have any broken links, just to name a few.
Is web scraping legal?
When you are web scraping publicly accessible factual data, it is legal. Always read and follow your target's Terms of Use and robots.txt file. Always consult your lawyer before scraping a target.
Is scraping Amazon legal?
Even though Amazon doesn't preach it, it is legal. Prices, reviews and what-not are all available to everyone anyway.
What is the difference between spider and crawler?
Spider and crawler can be used interchangeably when referring to a software used for web crawling. It can also sometimes be called an automatic indexer.
Is scraping and crawling the same thing?
While they sound very similar, they are not the same. Web crawling is a way to get the information and organize it, while web scraping can get very specific data and store it for later use.