So, you're struggling with CAPTCHAs and other blocks while scraping? That's actually understandable because we've also been there. With these 7 tips, you can rest assured knowing you won't get blocked.
- Quick solution: Easiest way to web scrape.
- Tip #1: Use proxies.
- Tip #2: Randomize crawling actions.
- Tip #3: Rotate User Agent headers.
- Tip #4: Implement fortified headless browsers.
- Tip #5: Use a CAPTCHA-solving service.
- Tip #6: Respect robots.txt.
- Tip #7: Scrape during off-peak hours.
Let's dive right in and discuss these crawling tips in detail!
Common Web Scraping Challenges
The first step to avoiding blocks during data extraction is understanding the challenges you'll encounter during scraping. Most websites employ different methods to stop you from scraping their data. Here are the common ones:
- Request header analysis: Deployed anti-bot measures often analyze the request headers to detect and block unusual or bot-like patterns.
- IP tracking: Websites track your IP address to block suspicious traffic, such as unusual request spikes or requests beyond the permitted threshold.
- CAPTCHAs: A site can hide a page behind a CAPTCHA, which is difficult for bots to solve but easy for humans.
- Browser fingerprinting: Anti-bot measures often profile clients' requests to create a unique identity to spot and block known bot patterns.
- JavaScript challenges: A website can prompt your scraper to execute a script before accessing a target page.
Websites often combine these methods to strengthen their firewall. So, you can't tell what you're up against precisely at any point. The 7 web scraping tips below will help you avoid them altogether.
Quick Solution: Easiest Way to Web Scrape
The main downside of large-scale web scraping is that multiple requests can appear as spam, resulting in blocking. Some anti-bot measures are even more aggressive, blocking every scraping request they spot.
The best way to scrape data from a website and get around all data extraction challenges is to use a web scraping solution like the ZenRows Universal Scraper API. It uses cutting-edge technology to ensure you scrape at scale without encountering blocks.Â
With a single API call, ZenRows helps you to rotate premium proxies, optimize your request headers, evade fingerprinting, solve all JavaScript challenges, bypass CAPTCHAs and other anti-bot measures, and more. Being an API, it's also compatible with any programming language.
Let's quickly see how ZenRows works by using it to scrape this Antibot Challenge page.
Sign up on ZenRows to open the Universal Scraper API Request Builder. Paste your target URL in the link box and activate Premium Proxies and JS Rendering.
Select your programming language (Python, in this case) and choose the API connection mode. Copy the generated Python code and paste it into your script.
Here's what the generated Python code looks like:
# pip3 install requests
import requests
url = "https://www.scrapingcourse.com/antibot-challenge"
apikey = "<YOUR_ZENROWS_API_KEY>"
params = {
"url": url,
"apikey": apikey,
"js_render": "true",
"premium_proxy": "true",
}
response = requests.get("https://api.zenrows.com/v1/", params=params)
print(response.text)
The above code outputs the protected website's full-page HTML, proving you bypassed the anti-bot measure challenge:
<html lang="en">
<head>
<!-- ... -->
<title>Antibot Challenge - ScrapingCourse.com</title>
<!-- ... -->
</head>
<body>
<!-- ... -->
<h2>
You bypassed the Antibot challenge! :D
</h2>
<!-- other content omitted for brevity -->
</body>
</html>
Congratulations! 🎉 You just solved all potential scraping challenges with the ZenRows Universal Scraper API. You can now scrape any website without getting blocked.
Tip #1. Use Proxies
Proxies are services that hide your request behind another IP address so the server sees you as a different user.Â
Websites can track and analyze your IP address against known ones to detect bot-like patterns. They may also set a threshold on the number of requests or block IPs from specific regions. Exceeding this request threshold or trying to scrape such geo-restricted content can result in an IP ban.
A scraping tip around that is to use proxies. You should also implement IP rotation with your proxy to mimic different users per request for improved anonymity. However, manual proxy rotation can be time-consuming and unsustainable at scale.
The best solution to ease the technicalities of IP rotation is to use premium web scraping proxies. Most premium proxy services offer residential IP rotation out of the box, allowing you to mimic legitimate users. This feature is handy for strict anonymity, especially while scraping on a large scale over long periods.
Tip #2. Randomize Crawling Actions
Web scraping often involves repeating the same action. Actions such as clicking the same element multiple times, scrolling the same height repeatedly, or filling out a form too quickly can raise suspicion.
To avoid that, ensure you randomize your scraping actions to mimic human behavior. For instance, you can implement random clicks and mouse movements. Here are some ways to mimic human behavior during web scraping or crawling:
- Simulate mouse hover: Mimic how natural users move the mouse across the screen.
- Randomized scrolling: Randomly scroll different heights and pause within scrolling actions to mimic natural behavior.
- Set delays between actions: Humans often pause between interactions. Implementing random delays between activities like navigation or clicks can reduce suspicion.
- Click elements randomly: In addition to setting delays, clicking random elements across the page to mimic human behavior can prevent anti-bot detection.Â
Tip #3. Rotate User Agent headers
The User Agent is one of the essential request headers for web scraping. HTTP clients and headless browsers often send a bot-like default User Agent.Â
For instance, Python's Requests library uses the following default User Agent:
python-requests/2.31.0
This default User Agent appears bot-like and can quickly signal the website that you're using an automated script.
Anti-bots expect a real browser User Agent like the Chrome string below:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36
One way to avoid detection is to replace your scraper's default User Agent header with a custom one from a legitimate browser.
While replacing is an essential first step, you should consider rotating the User Agent strings to mimic different browser environments. Then, ensure the selected User Agents for scraping are current to avoid suspicion.
While rotating the User Agent, ensure it's consistent with other request headers. For instance, the platform name in the Sec-Ch-Ua-Platform header and the User Agent must match to avoid detection. Similarly, the information in the Sec-Ch-Ua header must match those in the User Agent.
A good approach is to group these headers and rotate them as a set to ensure consistency in version and platform.
Tip #4. Implement Fortified Headless Browsers
Headless browsers like Selenium, Playwright, and Puppeteer are essential for scraping dynamic web pages. However, they often expose bot-like fingerprints, such as the presence of a WebDriver, HeadlessChrome User Agent, and more. All these default attributes make them easily detectable.
Patching these fingerprints can significantly reduce the chances of detection. However, manually implementing custom evasion patches can be technical and time-consuming. Fortunately, these headless browsers have anti-bot stealth plugins and helpers to reduce the risk of detection.
Here are the evasion plugins/helpers for the most popular browser automation tools:
- Selenium: Use SeleniumBase with Undetected ChromeDriver.
- Puppeteer: The Puppeteer Stealth plugin.
- Playwright: It also has the Playwright Stealth plugin.
That said, these headless browsers take up extra memory due to browser instances. Fortunately, if using Puppeteer or Playwright for scraping, you can further power them with advanced evasions and scalability using the ZenRows Scraping Browser. It's an efficient cloud-based infrastructure that allows you to run multiple browser instances concurrently in the cloud without impacting your local machine.
Tip #5. Use a CAPTCHA-Solving Service
CAPTCHAs are among the most used anti-bot techniques for detecting and blocking web scrapers. They can be puzzles or riddles that allow the site to distinguish humans from robots. While humans find the challenges easy to solve, bots usually struggle.
To prevent your crawler from falling through the cracks, you can resolve CAPTCHAs with solutions like 2Captcha, CapSolver, or Anti Captcha. However, the best and cheapest option is to save time by avoiding CAPTCHAs so your scraper runs smoothly. Some of the crawling tips to bypass CAPTCHAs are:
- Use CAPTCHA proxies.
- Don't send unlimited requests from a single IP. Change the pattern and timings of requests to make sure timeouts look organic.
- Improve the image of your web scraper. Try to obtain a database of legitimate user agents, delete cookies when unnecessary, align with TLS settings and HTTP headers, etc.
Tip #6. Respect robots.txt
Another important consideration is understanding robots.txt. Websites use this file to instruct search bots like Google on how to crawl and index their pages. They explicitly forbid bots from crawling certain pages, and scraping such restricted pages violates the website's terms.
One of the essential tips for web scraping is to follow the instructions in the robots.txt file to prevent legal repercussions and blocklisting.
Tip #7: Scrape During Off-Peak Hours
The server load of your target site is usually at its maximum during peak periods. Bots are also generally more aggressive within those hours. Besides risking detection, scraping during these times can affect the website's performance.
To significantly boost your chances of getting blocked, scrape only outside peak hours when most users are off the site. With fewer users online, server load is lower, and anti-bot defenses may be less aggressive.
Conclusion
We've covered 7 best data scraping techniques to get data from any website without detection. Since websites use several measures to block scraping, combining these tips is essential for successful data extraction.Â
However, while some of these web scraping tips are easy to implement, antibots can become increasingly challenging to bypass at scale, considering their frequent security updates. The easiest way to handle web scraping challenges efficiently at scale is to use a web scraping solution like ZenRows, an all-in-one scraping toolkit.