How to Avoid Getting Blocked: Best Practices for Web Scraping | Vertex

Web scraping is a powerful technique, but it’s a cat-and-mouse game. Websites deploy sophisticated anti-bot measures, and a naive scraper will get blocked almost instantly. The key to successful scraping is not just to be fast, but to be smart and respectful. Here are essential best practices to keep your scrapers running smoothly.

1. Rotate Your IP Address (The Golden Rule)

This is the most critical step. Sending thousands of requests from a single IP is the biggest red flag for any anti-bot system. Use a rotating proxy service to spread your requests across a large pool of different IP addresses. For difficult targets, rotating residential proxies are the gold standard.

# Example using Python's requests library with a proxy
import requests

proxy_url = "http://user:password@your_proxy_service:port"

proxies = {
   "http": proxy_url,
   "https": proxy_url,
}

target_url = "https://example.com"

response = requests.get(target_url, proxies=proxies)
print(response.text)

2. Mimic Human Behavior

Real users don’t fire off requests every 10 milliseconds. Your scraper shouldn’t either.

Randomize Delays: Introduce random delays (e.g., between 2 to 10 seconds) between your requests.
Set a Realistic User-Agent: Rotate through a list of common browser User-Agent strings. Don’t use the default User-Agent of your HTTP library.
Respect robots.txt: While not a technical requirement for avoiding blocks, respecting a site’s robots.txt file is an ethical best practice. It tells you which parts of the site the owner does not want you to crawl.

3. Handle CAPTCHAs and JavaScript Challenges

Modern websites use services like Cloudflare or Akamai that present JavaScript challenges or CAPTCHAs. While some proxy services offer solutions to bypass these, another approach is to use a headless browser like Puppeteer or Playwright, which can render JavaScript just like a real browser. However, be aware that these tools are more resource-intensive.

4. Scrape Off-Peak Hours

To be a good web citizen, try to run your scrapers during the target website’s off-peak hours (e.g., late at night). This reduces the load on their servers and makes your traffic less noticeable.

Conclusion

Successful web scraping is about being stealthy and considerate. By combining a high-quality rotating proxy service with intelligent scraping logic that mimics human behavior, you can gather the data you need without disrupting the websites you’re targeting.