3 Issues That Slow Your Web Scraping Process
Web scraping can be a valuable technique for any business that relies on large datasets to grow. However, the web has evolved, and sometimes you get blocked by obstacles when trying to extract valuable data from the Internet.
While some websites are easy to scrape data from, others have measures to stop you from collecting information. Not only that, but you can also encounter some issues that are related to the way your scraper is set up.
This article will briefly explore the most common problems people encounter when trying to web scrape and talk about the solutions. Web scraping is not hard. But with of bit o coding knowledge, patience and practice, you can make sure to never encounter these problems again.
Before diving into the most familiar web scraping problems, let’s see what this process brings to the table.
The benefits of web scraping
Web scraping tools are extremely helpful to extract large amounts of data to optimize your business. Here’s a brief primer on why to stop collecting data manually.
Businesses use web scraping for many different purposes. It can be used for lead generation, market research, price optimization, and machine learning, among many others.
Apart from its speed, web scraping also guarantees that the data is way more accurate than when manually copying and pasting the information. It saves your resources and you can concentrate on other essential tasks.
However, no matter the benefits, you will almost certainly encounter websites that don’t want to be scraped. These are the web pages that usually set up countermeasures to detect and block what they deem suspicious activity. Apart from that, your will encounter other unexpected problems that you should be aware of. Let’s explore the main issues you will encounter when you extract data from a website.
Common challenges of web scraping
Technically, all websites are scrapable if you have the skill and knowledge to do it. But, some data is harder to collect. Certain web admins can be overly protective of their websites and implement techniques to keep you from gathering information from their pages. So let’s take a look at common obstacles when trying to extract data from the Internet.
HTTP 4xx response codes
These responses are usually triggered by a rate-limiting technique put in place by webmasters to guard against activities like web scraping. The most common one is the 429 response, which generally indicates that the website detected you and is trying to stop you.
In some cases, slowing down the rate at which you scrape can solve the issue. However, sometimes you need to implement some changes into your scraping strategy.
The first thing you need to consider when receiving these types of response codes is rotating proxies. Sending many requests from the same IP can trigger detection. That’s why it’s important to use a proxy rotation service, which changes your IP with every request. Familiarizing yourself with proxies can be valuable, as it provides you with an excellent way to optimize your scraping process. Nevertheless, there are generally two types of proxy IPs you should be aware of.
Datacenter proxies are cloud-based IPs with no actual location. They are relatively inexpensive and are built on modern infrastructure. However, these proxies can be used by multiple users simultaneously, making them easier to detect.
Residential proxies are more reliable and expensive because they are real IPs provided by Internet providers with actual locations. They make your requests impossible to block by imitating regular visitor activity.
Another great tip to avoid these response codes is to make your scraping look like regular user activity. One way of doing this is to include a degree of randomness. A repetitive and predictable scraping method is a definite sign that a bot is browsing the website. To avoid this, try to add random delays between requests and avoid linking all requests in one extensive sequence. Another great alternative is to scrape different URLs in the same session but not simultaneously.
Partial data collected
If you only collect parts of the needed information when extracting data, your scraper might be blocked by a CAPTCHA. Here’s how to bypass this common verification technique.
CAPTCHAs can come in various shapes and sizes. They can be a simple math problem or a word or image identification game. For us, solving them is easy. However, these tests are difficult for bots because they are made to verify that an actual human is doing the browsing.
So what can you do? You can use a Captcha solving service. Some websites employ people to solve them for you. Or, you could use a different proxy. But this solution would require access to a reliable proxy pool. To understand the importance of a great proxy pool in web scraping, check this article out.
Regardless of how you solve a Captcha, keep in mind that removing the obstacle gives you access to the data, but it does not prevent you from being detected by the website. On the subject of CAPTCHAs, the best medicine is prevention.
Getting honey potted
If you find yourself getting the wrong information, you have probably fallen for what is called a honeypot. These are traps set up by web admins in the form of links in the HTML. They are not visible to an average user, but web scrapers will request them and get blocked.
These traps can redirect your tool to endless blank pages and fingerprint the properties of the scrapers request, which is essentially blocking your activity. Let’s see how to avoid this popular countermeasure.
First, keep in mind that webmasters tend to change their honeypot URLs and site attributes constantly, so make sure your scraper is up to date and can tackle this obstacle. If you’re using a pre-made scraper, check to see that it has all the necessary elements to bypass the honeypots.
Also, make sure to follow only visible links when scraping. If you think your scraper has already taken the bait, look for “display: none” or “visibility: hidden” CSS properties in a link.
Knowing what to do when you get stuck web scraping is essential for getting as much data as possible. From less than ideal practices to website countermeasures, your need to have a kit of neat tricks prepared for all your scraping endeavors.
You’ll probably encounter more problems along the way. But knowing where to start with fundamental web scraping issues can make the process a little easier and more effective.
If you are ready to start scraping but don’t know how to start, we recommend reading this comprehensive list of tools.