5 Web Scraping Challenges
Web Scraping has become very common nowadays days as the demand for data extraction has gone up in recent years. You can pick any industry and you will find one thing in common and that is web scraping. But web scraping at scale can be a little frustrating as many websites around the world use on-screen data protection software like Cloudflare.
In this post, we will discuss the five most common web scraping challenges that you might face in your data extraction journey. Let’s understand them one by one.
CAPTCHAs
CAPTCHA is a Completely Automated Public Turing Test to Tell Computers and Humans Apart. Captchas are the most common kind of protection used by many websites around the world. If an on-screen protection software thinks the incoming request is unusual then it will throw a captcha to test whether the incoming request is from a human or a robot. Once confirmed it will redirect the user to the main website.
Captcha helps to distinguish humans from computers. This is a kind of test that a computer should not be able to pass but it should be able to grade. It is kind of a paradoxical idea.
There are multiple captcha-solving softwares in the market that can be used for solving captchas while scraping but they will slow down the scraping process and the cost of scraping per page will also go up drastically.
The only solution to this problem is to use proper headers along with high-quality residential proxies. This combination might help you bypass any kind of on-site protection. Residential proxies are high-authority IPs that come from a real device. The header object should contain proper User-Agent, referer, etc.
IP Blocking
IP blocking or IP bans are very common measures taken by website security software. Usually, this technique is used for preventing any kind of cyber attack or other illegal activities. But along with this, IP bans can also block your bot which is collecting data through web scraping. There are mainly two kinds of IP bans.
- Sometimes website owners do not like bots collecting data from their websites without permission. They will block you after a certain number of requests.
- There are geo-restricted websites that only allow traffic from selected countries to visit their website.
IP bans can also happen if you keep making connections to the website without any delay. This can overwhelm the host servers. Due to this, the website owner might limit your access to the website.
Another reason could be cookies. Yes! this might sound strange but if your request headers do not contain cookies then you will get banned from the website. Websites like Instagram, Facebook, Twitter, etc ban the IP if cookies are absent in the headers.
Disabled Javascript can also cause IP bans. When you render JS website thinks you are a real person and not a bot.
You can identify your IP ban if you start getting a 404 page or a captcha.
There is only one way to avoid IP bans and that is to use a pool of millions of proxies. Make every request through a new IP. This will help you extract data without getting blocked.
Dynamic Websites
Many websites use AJAX to load content on their website. These websites cannot be scraped with a normal GET request. In AJAX architecture multiple API calls are made to load multiple components available on the website.
To scrape such websites you need a chrome instance where you can load these websites and then scrape once they have loaded each and every component. You can use Selenium and Puppeteer to load websites on the cloud and then scrape it.
The challenging part is to scale the scraper. Let’s say you want to scrape websites like Myntra then you will require multiple instances to scrape multiple pages at a time. This process is quite expensive and requires a lot of time to set up. Along with this, you need rotating proxies to prevent IP bans.
Instead of this, you can use Web Scraping API to scrape dynamic websites at scale without handling headless chrome and proxies. This will save you time and money.
Change in Website Layout
In a year or so many popular websites change their website layout to make it more engaging. Once that is changed many tags and attribute also change and if you have created a data pipeline through that website then your pipeline will be blocked until you make appropriate changes at your end.
Let’s say you are scraping mobile phone prices from amazon and one day they just changed the name of the element that holds that price tag then eventually your scraper will also stop responding with correct information.
To avoid such a mishap, you can create a cron job that can run every 24 hours just to check if the layout is the same or different. If something changes you can shoot an alert email to yourself and after that, you can make the changes you need to keep the pipeline intact.
Even a minor change in the website layout will block your scraper from returning appropriate information.
Honeypot Traps
Honeypot is a kind of system that is set up as a decoy, designed to appear as a high-value asset like a server. Its purpose is to detect and deflect unauthorized access to website content.
There are mainly two kinds of honeypot traps:
- Research Honeypot Traps: close analysis of bot activity.
- Production Honeypot Traps: It deflects intruders away from the real network.
Honeypot traps can be found in the form of a link that is only visible to bots but not humans. Once a bot falls into the trap, it starts gathering valuable information(IP address, mac address, etc). This information is then used to block any kind of hack or scraping.
Sometimes honeypot traps use the deflection principle by diverting the attacker's attention to less valuable information.
The placement of these traps varies depending on their sophistication. It can be placed inside the network’s DMZ or outside the external firewall to detect attempts to enter the internal network. No matter the placement it will always have some degree of isolation from the production environment.
Conclusion
This article covered the most common web scraping challenges that you might face in your web scraping journey. Obviously, there are many more such challenges in the real world.
We can overcome all these challenges by changing the scraping pattern. But if you want to scrape a large volume of pages then going with Web Scraping APIs would be great.
We will keep updating this article in the future with more challenges. So, bookmark this article and also share it on your social media pages.
