Table of Content
- Can you get blocked for web scraping?
- Why Does a Web Scraper Get Blocked?
- How to Avoid Being Blocked or Blacklisted During Web Scraping
- Wrap Off
Is your web scraping project getting blocked, or are you wondering how do I stop being blocked from web scraping? In this article, you will gain insight into five tried and tested tips to reduce the chances of being blocked when scraping websites.
Can you get blocked for web scraping?
Yes, you can. During web scraping, you may come across a situation where the website asks you to prove that you are not a robot using the Google reCAPTCHA or similar services, or even worse — a code verification.
Other times, your web scraper might get downright rejected from accessing a particular website. This situation occurs when the website you want to scrape is trying to identify or has already identified you as a scraping bot. When a website terms a user or request as a web scraper, it will blacklist all visits and requests from that user
Why Does a Web Scraper Get Blocked?
Everyone in the scraping community knows that web scraping is a way to extract data from websites, and it is much more effective than copying and pasting manually. However, some people seem to forget that it comes at a price for the site owners — an expensive one.
A straightforward example is that web scraping may overload a web server causing a server breakdown.
To prevent such a situation, more and more site owners have equipped their websites with all manners of anti-scraping techniques, which makes web scraping even more difficult.
How to Avoid Being Blocked or Blacklisted During Web Scraping
There are ways to prevent web scrapers from getting blocked. Let's take a look:
Switch user agents
A user agent is like an identification fingerprint. 1. It helps the internet identify which browser is in use. Your browser sends a user agent header to the website you visit.
When visiting a website as a scraping agent, a website would block numerous requests from the same user agent. To circumvent this, you can switch user agents frequently.
Most programmers who carry out web scraping add a fake user agent in the header when making the request or manually create a list of user agents to avoid being blocked.
Slow Down Web Scraping Request Speed
Most programmers configure their web scrapers to get data as quickly as possible. However, that is inorganic and does not represent how humans use a website.
You see, when a human visits a website, their browsing activity is much slower than that of a robot. Therefore, some websites detect a web scraper by tracking its exact speed.
When it discovers an ongoing browsing activity or request that is unusually fast, it will suspect that you're not a human and block your request naturally.
To avoid this, you can add some time delay between requests made by your web scraper and reduce concurrent page access to one or two pages at a time.
You can also do this by setting up a wait time between each step to control the scraping speed.
Better yet, you can set up a random time delay to make the scraping process appear more like it is done by a human.
Be nice to the website, and you'll be able to keep scraping.
Use Proxy Servers
When a website detects several requests coming from a particular IP address, it will easily blacklist the IP address.
To avoid sending all of your requests from the same IP address, you can use proxy servers.
The proxy server acts as a middleman. It retrieves data on the internet on behalf of the user, in this case, the web scraper.
It also allows you to send requests to the website using the IP you set up and masking your original IP address from being blacklisted if the proxy fails.
Likewise, it is worth noting that if you use a single IP address setup in the proxy server, it will be too easy for the web scraper to get blocked.
You need to create a pool of IP addresses and use them randomly to read your requests through a series of different IP addresses.
To get new IP addresses, there are many servers you can use, such as VPNs. Web scraping tools usually make it fairly easy to set up IP rotation in a crawler to avoid being blocked.
Some even allow you to set up the time interval for IP rotation and enter the IP addresses manually.
Another approach to prevent your IP address from being blacklisted during web scraping is to use cloud extraction. It is supported by hundreds of cloud servers, with a unique IP address for each.
When a web scraper executes on the cloud, requests are performed on a target website through various IP addresses, minimizing the chances of being traced.
Clear your Cookies
A cookie is like a small document containing information about you and your browsing preferences.
For instance, if you are a native English speaker. When you open a website and change the preferred language to English, the website sets a cookie to remember your preferred language as English.
From there on out, until you change the preference, every time you open the website, it will automatically set the preferred language as English.
So, how do cookies affect your web scraping?
If you are scraping a website constantly with the same cookie, the website can easily detect you as a bot.
It is advisable to clear cookies from time to time.
Some web scraping tools make this easy by allowing you to either customize the time interval for switching user agents or combine this with the other technique listed above and clear cookies 1. when switching IP addresses or user agents.
Look out for Honeypot Traps
Honeypot traps are links that are invisible to regular website visitors, but they exist in the HTML code and can be found and picked up by web scrapers.
They are traps set by website owners to detect web scrapers by directing them to blank pages.
Once a honeypot page is visited, the website can detect it is not a human visitor and start throttling or blocking your requests from that client.
When building a web scraper, it is worth looking carefully to check for the presence of anchor links hidden from users
You can do this by manually using a standard browser beforehand to click and capture the web page content.
You can also do this programmatically by using XPath to locate specific elements on a page.
XPath, the HTML Path Language, is a query language used to navigate through elements in an XML document. All the web pages are HTML documents in nature.
Most modern web browsers support XPath. Some programming and web scraping tools allow the use of XPath to locate data on web pages precisely.
It will help prevent your web scrapers from accessing the false links and avoid being blocked.
Those are the five anti-blocking techniques we have discussed. If you find this article useful, please consider sharing it.
What other anti web scraper blocking techniques do you use? Hit me up on any of my socials and let us talk tech.