How to Prevent Blacklisting When Scraping

How to Prevent Blacklisting When Scraping

Last Edited August 21, 2018 by Garenne Bigby in Search Engine Optimization

Scraping websites is almost exactly how it sounds—the website content is viewed quickly, and necessary information is gathered and then put into a spreadsheet. The specific information needed is taken and then added to a database where scrapers can store the data. Companies that scrape information from websites can benefit from using this data by being able to keep up with the competition, centralizing data quickly and efficiently, and pricing analytics. The process also allows for loads of unstructured data to be arranged in a more organized way. It allows businesses to gather and analyze useful data that is out there on the internet.

People who perform web scraping are called, web crawlers, scrapers, or spiders. These terms are all used interchangeably. These people and robots who scrape can have a negative effect on the performance of a website and the process of collecting true data when it comes to web pages. Since this is a large part of gaining popularity on the internet, if scraping is not done properly, it can cause the site to be blocked for the crawler.

Site administrators are not usually pleased with this process, which can cause them to detect and then block this from happening. Some site administrators might even use tools to detect and keep scrapers away. There are many strategies that web scrapers can use to overcome these blockages. Having anti-scraping mechanisms installed on a website might affect a user’s experience, but there are people out there who do not agree with this website data being out in the open.

Below is important information to understand how websites detect scraping, how to figure out if you have been blocked, and ways to prevent being blacklisted. Follow these steps below to prevent blacklisting when scraping, so you can still have access to the important information that is needed. There are ways around being blacklisted when scraping. It takes careful work to work around being blocked from a website, especially when one has been blacklisted, but it can be done.


How Do Websites Detect Scraping?

It can be helpful to understand the process as a whole, so how do websites detect scraping? There are a few different factors that can affect how websites know scraping is happening. If a website is experiencing a high download rate or being visited numerous times from the same IP address, this is one way its administrators can detect scraping. This unusual traffic pattern may happen over a short time span, which can be an important clue to determining that scraping is taking place.

Another way to detect web scraping is when the same tasks are being performed over and over again on a website. This is especially true when robots are being used to do the scraping. These repetitive tasks will likely not be taking place with normal users, so when it happens, that can be another clue. If a human user is visiting a website, it is safe to say that these tasks will not be performed over and over again.

Honeypots are another way that websites can detect scraping. Honeypots are links that aren’t available to normal users, only a web scraper. If a web scraper attempts to use these links, an alarm goes off for the website that a scraper is doing their job. Normal users are not able to find where the honeypots are, so when they are clicked on, a web administrator is automatically notified that this is happening.


How to Figure Out a Website Has Blocked a User

In order to figure out how to work around being blocked, you must first understand how to figure out if you are blocked or not. Being blocked from a website can be very frustrating, especially when trying to get important information. Being blocked from a website means that the user will not be able to see the content on the website or interact with it in any way. If you are blocked, a notification will show up when you try to visit the page. Some of the notifications that will show up might be:

  • CAPTCHA pages

  • Delay of content delivery

  • Error responses that keep showing up with HTTP 404, 301 or 50x errors


You also might see some of these codes within the notification:

  • 503 Service Unavailable

  • 429 Too Many Requests

  • 408 Request Timeout

  • 404 Not Found

  • 403 Forbidden

  • 401 Unauthorized

  • 301 Moved Temporarily

There might also be other similar messages that have a 3-digit number on the front. With many other codes that can indicate you have been blocked or banned from a website, it is important to become familiar with the codes. It can be helpful to know these codes if you are considering web scraping. If you are banned from a website, it can be permanent, or it can be temporary. This will depend on the website and the violation. Give it time and visit the website again later. If still banned, it could be a permanent situation. Keep reading to find information on what you can do to prevent being blacklisted from websites.


Prevent Being Blocked by Being Kind

Kindness always wins. This is also true when you are scraping the web. You should be able to read through a website’s web crawling policies by looking at the information on the page before you do anything else. Take some time to search through the website before beginning your agenda. There is usually information found on the website in the section that talks about their user agreement.

By following a website’s crawling policy, you can be sure you will not get banned or blocked from using it. It is always important to follow the rules, especially when they are posted. While the rules of web scraping are not always posted, you should be careful and follow these other guidelines to ensure you are not banned or blocked.


Do Your Research

By looking up information about how to prevent blacklisting while scraping the web, you are already working towards ensuring you won’t get banned. The best way to prevent anything from happening is to be prepared and do your research. There is no better protection. Understanding the process, rules, and web scraping etiquette will help to ensure being blocked or banned won’t happen to you. Before moving forward and performing your web-crawling agenda, get all the information that can be helpful to make sure nothing happens. It is important to understand the process, so you don’t make any mistakes.

While web scraping is a process that may take some time to learn, the more you understand the process and know what to do, the better your results will be. Understanding the rules and etiquette will help you to be able to follow them. People can’t follow the rules if they don’t know what those rules are. Read through the rest of the rules and etiquette below, so you can understand what you should and should not do when it comes to web scraping.


Be Knowledgeable about Honeypots

Honeypots are links on a website that can be seen by regular users, but not by spiders or web crawlers. These “traps” are put in their purposely to detect when someone is attempting to scrape on their website. Being careful with the links clicked on when visiting a site will help you be able to detect the honeypots before they become a problem. If there is a link you want to click on, hovering the mouse over the link can reveal where the link will go. It is a good idea to do this to make sure you are not falling into a honeypot trap.

This security “alarm” is mostly used when sites do not allow web scraping. In a way, it is used to lure someone to click on it, so they can be caught. There is some good news, though. Since this can be a difficult feature for web administrators to implement, many sites do not have honeypots. The bad news is that they can be out there when you least expect it.

By understanding and being knowledgeable about honeypots, you are already doing a great job of preventing yourself from falling victim to this security feature that is out there on the web. It is important to be vigilant and knowledgeable about honeypots before they become a problem and prevent your agenda from being carried out.


Switch Up Your Scraping Pattern

It might not be known that when visiting a website, human users follow all sorts of patterns to get the information they need. A crawling pattern can be what sets off website administrators that scraping is taking place. If a pattern is the same each time a user visits the webpage, this can be a big indication that web scraping is happening. A website owner who cares a great deal about web scraping will most likely have someone monitoring the activity on their site. If robots are performing scraping, it will be evident because they will usually follow the same exact pattern every time they visit the website. This can be a red flag for someone monitoring and trying to prevent scraping from happening on websites.

There are anti-crawling tools out there on the web as well that can detect scraping when it happens. As a human performing web scraping, make sure you are switching up the pattern you follow when you visit a website. This can be a great way to prevent blacklisting. To switch up your pattern, perform other random clicks that don’t have to do with scraping. Making sure to mimic that of a regular user visiting a web page while also doing the job you need to. While it does seem like it could take a bit more time and planning, it will be beneficial in the end when you can get the information you need without being banned from a website.


Be Respectful When It Comes to Robot.txt File

You may or may not find a list of rules and regulations on some websites called a Robot.txt file. A Robot.txt file will explain the rules of how to perform crawls on their website. If there is a Robot.txt file for a webpage you are visiting, make sure to follow all the rules laid out in that file. The file might indicate which information and pages can be scraped, the frequency of how often robots can perform scraping tasks, and any areas that should be avoided during the process.

By following the rules laid out in this file, you can prevent yourself from being blacklisted. It is important to note that certain websites may allow Google to perform web scraping, but not other users. While it might seem that practice is unfair, website owners are well within their rights to make this call. Some want to support Google’s efforts to get information that can help to make the internet better, but do not want their information to go elsewhere. While this can be frustrating, you will need to respect the Robot.txt files that are out there on the internet.


Use Browsers That Are Headless

Another way blacklisting can be prevented is by using a headless browser. A headless browser is one that works like any other browser; only they aren’t visual on a desktop. This can help you to stay undetected when performing web scraping duties. Interestingly enough, certain browsers will display different information for different websites, so that is also something to know when it comes to using headless browsers.

Depending on the web browser being used, there could be other additional or enhanced content that is displayed. Google has a headless browser option, and there are other headless browsers you can explore as well. Selenium and Python are also two other headless browsers that can be used when web scraping in order to avoid blacklisting. You can get additional information to find out which headless browser will be most helpful to you.


Switch Up IPs and Proxy Servers

Often, when user data is collected from a website, it is easy to see the IP address of the user that is visiting. This allows websites to collect information about what certain users are doing. They will often collect data based on what patterns users are following, how their user experience is, and if they are returning or first-time users. When one IP address or proxy server shows the same user patterns over and over again, a website may pick up on the web scraping. When this is detected, there is a higher chance you may be blocked from visiting a website.

Multiple requests from the same user will cause trouble with the web administrator, and this is what causes blacklisting. If there is an option to have multiple IP addresses, this can be another technique that will prevent blacklisting. To switch up your IP address and proxy server, you can use a VPN. Virtual private networks (VPNs) are servers that can disguise or change your IP address. This will allow web scrapers to get their information without being detected as easily.


Read Over Terms and Conditions

As mentioned before, it is important you are aware of the terms and conditions of the websites. Playing by the rules is really the only way to prevent yourself from being blacklisted completely. Many websites include their web scraping rules in a terms and conditions section on their website. This can prevent scraping for those that play by the rules. While they may or may not allow anyone to scrape their information, it is important that you are aware of what the policies are.

It is understandable that not everyone plays by the rules, but if a website has terms and conditions related to web scraping, then they should be followed to the best of your ability. Following a website’s terms and conditions can definitely help a web scraper from being blacklisted.


Final Words

Preventing blacklisting when scraping is not too difficult if you are doing research and following the rules. There are also other strategies you can use to detect or prevent becoming blacklisted. Collecting the data and information on the web is very important to keeping up with your competition, analyzing pricing, and putting data in a central location for easy access. These goals cannot be reached if you are blacklisted from websites. This would mean you no longer have access to the information.

Whether you are performing web scraping or having it done by a robot, there are steps you can follow to make sure you still have access to websites. By doing your research, understanding the terms and conditions, and knowing what a honeypot is, you can be knowledgeable about what you can and can’t do. You can also use strategies such as changing your user patterns, using headless browsers, and switching your IP address. The best way to prevent blacklisting is to understand and read through the terms and conditions and to make sure to be kind.

Garenne Bigby
Author: Garenne BigbyWebsite: http://garennebigby.com
Founder @dynomapper
Garenne Bigby is freelance Chicago developer and founder of DYNO Mapper with over 10 years experience in both agency and freelance roles in design, development, user experience, SEO, and information architecture.

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