Web scraping has become essential for data collection for many industries, including e-commerce, finance, marketing, and research. However, it can be a tricky business, as it often results in being blocked by anti-bot systems.
Unfortunately, that can hinder your progress and waste valuable time and resources. Below, you’ll learn why that happens and the best techniques to web scrape without getting blocked.
Why Do Scrapers Get Blocked
Before diving into the techniques to avoid detection while web scraping, it’s essential to understand why scrapers get blocked in the first place. Here are the most common reasons:
One of the main reasons why web scrapers get blocked is due to heavy traffic. When a website receives a high frequency of requests in a short time, it can trigger an alarm in the system. That can be especially true for websites not optimized for high traffic, such as smaller e-commerce websites.
Many websites can easily detect whether users interact with them via an automated tool, like a scraper. Once they identify such activities, they may block the user. For example, some websites may monitor the frequency and timing of requests and the sequence of actions taken by the scraper. If the requests appear automated, the website may block the user.
Every IP is assigned a score based on various factors when visiting a website with anti-bot measures. That includes behavioral history, association with bot activity, geolocation, etc. Depending on that data, your scraper may get flagged and blocked.
Some websites intentionally place hidden links and pages to trap web scrapers. When the bots attempt to access these pages, they get blocked. For example, there may be a hidden link to a page that contains a fake product or review. If the scraper attempts to access this page, the website will block it.
Websites often use browser fingerprinting to detect automated tools. This technique collects information about a user’s browser and operating system, such as the User Agent, language, time zone, and other browser information. If the website determines the fingerprint matches a scraper’s, it’ll block the user.
CAPTCHAs are one of the most common methods for websites to detect and block scrapers. They’re designed to test whether a user is human by presenting them with a challenge difficult for automated tools to solve, such as identifying a set of images. If the scraper fails to solve it, the website will block it.
As you can see, websites have many techniques to identify bots and deny their access. That’s why it’s important to know how they work to implement strategies to avoid detection.
How to Avoid Getting Blocked While Web Scraping
Now that we understand why web scrapers get blocked, we’ll discuss some techniques to avoid that.
Use an API to Bypass Anti-bot Systems
Anti-bot systems can be bypassed by implementing techniques such as spoofing the browser, randomizing timings between requests, and using a different User-Agent on every request.
ZenRows’ web scraping API does all this and more to ensure you get the data you want from any protected website. You can integrate it into any workflow, as it works seamlessly with all programming languages.
Use Headless Browsers and Stealth Plugins
Using headless browsers can make it difficult for websites to detect automated tools. They don’t have a user interface and are programmed to simulate human interactions effectively. However, they have automation markers that anti-bot systems can easily detect. The solution is using plugins to mask these properties to scrape uninterrupted.
Use Custom and Rotating Request Headers
The HTTP request headers contain key information about the client making the request. Therefore, one of the most effective ways to bypass anti-bot monitoring is to set real request headers. That involves mimicking a real user by including headers like User-Agent, Accept-Language, Accept-Encoding, etc.
Otherwise, your scraper will get blocked if your headers are incorrectly formed or mismatched. Another necessary step is to rotate different headers for every request to avoid raising suspicion.
Use Premium Proxies
Using proxies can be a great way to bypass IP blocking. By using different IP addresses, the requests from the scraper will appear from other users, making it harder for the website to detect and block them.
Although using free proxies can be tempting, they’re often unreliable and can be easily detected by anti-bot systems. On the other hand, Premium proxies offer residential IP to provide higher anonymity and help you fly under the radar.
CAPTCHAs are one of the most common methods websites use to detect and block scrapers. You have two options in that regard: solve them or avoid triggering them.
If you decide to go with the former, you can use solving services, which employ real people to pass the challenges for you. However, that can be quite costly if you scrape at scale. On the other hand, if you upgrade your bot to act as human-like as possible, you won’t have to deal with them at all.
Avoid Browser Fingerprinting
Websites can use browser fingerprinting to detect automated tools. That involves collecting information about a user’s browser and operating system.
Using different User Agents, languages, time zone, and other browser information that mimics a human is recommended to avoid that. Another good rule of thumb is to send your requests at different times every day and forge and rotate TLS fingerprints often.
Avoid Honeypot Traps
Honeypot traps are designed to attract bots but can be avoided. You can implement techniques like analyzing the links, avoiding hidden ones, and looking for specific patterns in the HTML code to that end.
Many industries rely on web scraping for data collection, but it has its challenges. Most modern websites employ anti-bot systems to detect and block malicious traffic, which, unfortunately, denies access to scrapers.
You can take the time to fortify your scraper using the techniques outlined above or choose an easier and more resource-efficient option: ZenRows. This web scraping API comes with an advanced anti-bot bypass toolkit that can ensure the success of your project. Use the 1,000 free API credits to test it out.