How to Crawl a Website Without Getting Blocked

Learn how to crawl a site without getting blocked by following these 8 tips. Avoid IP bans, CAPTCHAs, and honeypots with web scraping best practices.

How to Crawl a Website Without Getting Blocked
Sharon Bennett
Sharon Bennett 8 min read
Article content
  1. Check and follow the robots.txt file of the website
  2. Use a proxy server and rotate IP addresses frequently
  3. Use real and diverse user agents and browser headers
  4. Avoid sending too many requests in a short period of time
  5. Use a delay or random interval between requests
  6. Use a headless browser or a web scraping tool that can handle dynamic content
  7. Solve CAPTCHAs automatically or manually if needed
  8. Avoid following hidden links or elements that may be honeypot traps
  9. Frequently Asked Questions

Site crawl is the process of extracting data from websites for various purposes, such as market research, price comparison, content aggregation, etc. However, web crawling can be challenging, especially when websites use anti-scraping techniques to prevent or limit data extraction. In this guide, you will learn how to crawl websites without getting blocked by following 7 tips. These tips cover topics such as robots.txt file, proxy servers, IP rotation, user agents, browser headers, request delays, dynamic content, CAPTCHAs, and honeypot traps. By applying these tips, you will be able to crawl a site more efficiently and ethically.

Tip 1: Check and follow the robots.txt file of the website

Web crawling bot reading robots.txt

The robots.txt file is a file that tells web crawlers which pages or files they can or cannot request from a website. You can find it by adding /robots.txt to the end of the website's URL – you can try following this link to see it for yourself: https://www.amazon.com/robots.txt. The file contains rules for different user agents (web crawlers) that specify which paths are allowed or disallowed for crawling.

🏸 Further reading: Responsible web scraping: An ethical way of data collection

For example, User-agent: * means the rule applies to all web crawlers, and Disallow: / means web crawlers cannot crawl all pages of a website. You should follow the rules of the website to respect its wishes and avoid getting blocked for violating them. However, some websites may still block you even if you follow the robots.txt file, so you should also use other techniques to crawl the site without getting blocked.

Tip 2: Use a proxy server and rotate IP addresses frequently

Web crawler connects to a website via a proxy

A proxy server is an intermediary between your device and the target website that hides your real IP address and location. Using a proxy to crawl websites reduces the chances of getting blocked by the website, ensures your anonymity, and allows you to access geo-restricted content. You should choose a reliable proxy crawler and use either datacenter or residential IP proxies, depending on your task.

🏸 Further reading: Rotating vs. static proxies

Datacenter proxies are faster and cheaper, but more easily detectable and banned. Residential crawler proxy is slower and more expensive, but more reliable and less likely to be blocked. Rotating IP addresses means changing your proxy IP address after each request or after a certain period of time. This makes you look like different internet users and prevents the website from detecting your bot when you crawl it with a proxy. You can use a proxy rotator service or choose a proxy provider that offers rotating IPs, such as Infatica’s residential proxies.

🏸 Further reading: Guide to efficient web scraping with residential proxies

Tip 3: Use real and diverse user agents and browser headers

Mobile and desktop user agents

User agents are strings that identify the browser, operating system, device, and other information about the client that is making the HTTP request. Websites can analyze the user agents of the requests and block those that look suspicious or fake. To avoid this, you should use real user agents that match the browser and device you are using, and change them frequently to perform web scraping without getting blocked. You can find lists of real user agents online, such as User Agents Database.

🏸 Further reading: User agents in web scraping: How to use them effectively

Browser headers are additional information that is sent along with the HTTP request, such as cookies, `referer`, `accept-language`, etc. Websites can also use these headers to verify the authenticity of the requests and block those that are missing or inconsistent. To avoid this, you should use realistic and diverse browser headers that match your user agent and the website you are visiting. You can use tools like https://httpbin.org/headers to check your browser headers.

🏸 Further reading: HTTP headers guide

Tip 4: Avoid sending too many requests in a short period of time

Gradual stream of web crawling requests

Websites often have limits on how many requests they can handle from a single IP address in a given time frame. If you exceed these limits, you may trigger their anti-scraping measures, such as IP rate limiting, CAPTCHAs, or bans.

To avoid this, you should limit the number of requests you send to the website and use a delay or random interval between requests. A good rule of thumb is to send one request per second or less, but this may vary depending on the website's capacity and tolerance. You can also monitor the response status codes and headers to see if the website is sending you any signals to slow down or stop.

Tip 5: Use a delay or random interval between requests

Web crawling requests appearing at random intervals

Websites often have limits on how many requests they can handle from a single IP address in a given time frame. If you exceed these limits, you may trigger their anti-scraping measures, such as IP rate limiting, CAPTCHAs, or bans. To avoid this, you should limit the number of requests you send to the website and use a delay or random interval between requests.

A good rule of thumb is to send one request per second or less, but this may vary depending on the website's capacity and tolerance. You can also monitor the response status codes and headers to see if the website is sending you any signals to slow down or stop. You can use libraries or tools that have built-in features to implement delays or random intervals, such as requests, Scrapy, or Infatica Scraper API.

Tip 6: Use a headless browser or a web scraping tool that can handle dynamic content

Regular and headless browsers

Some websites use dynamic content that is loaded or changed by JavaScript after the initial HTML response. This means that if you use a simple HTTP request library like requests in Python, you may not get the full or updated content of the page. To overcome this challenge, you can use a headless browser or a web scraping tool that can execute JavaScript and render dynamic content.

🏸 Further reading: Headless browsers 101: Data gathering made simple

A headless browser is a browser that runs without a graphical user interface (GUI) and can be controlled programmatically. Examples of headless browsers are Selenium, Puppeteer, Playwright, etc. A web scraping tool is a software or service that simplifies the web scraping process by providing features like proxy management, CAPTCHA solving, browser automation, data extraction, etc. By the way, Infatica’s Scraper API can handle dynamic content just fine!

Tip 7: Solve CAPTCHAs automatically or manually if needed

reCAPTCHA example

CAPTCHAs are tests that websites use to verify if the requester is human or not. They usually involve solving puzzles, typing words, or clicking images. If you encounter a CAPTCHA while web scraping, you have two options: solve it automatically or manually. Solving it automatically means using a service or a library that can recognize and solve the CAPTCHA for you. Examples of such services are Anti-Captcha, 2Captcha, DeathByCaptcha, etc. Examples of such libraries are pytesseract, captcha-solver, etc.

🏸 Further reading: Data gathering issues: How to deal with CAPTCHAs?

Solving it manually means using a human intervention to solve the CAPTCHA yourself or by someone else. This can be done by using a web interface, an API, or a browser extension. The choice between automatic and manual solving depends on the type, frequency, and difficulty of the CAPTCHAs, as well as the cost and time involved.

Tip 8: Avoid following hidden links or elements that may be honeypot traps

Web cralwers attracted to a honeypot trap

Honeypot traps are hidden links or elements that web crawlers may follow but humans would not. They are used to lure and identify malicious bots and block them from accessing the website. Examples of honeypot traps are links with invisible CSS styles, links with fake attributes, links with misleading text, etc.

🏸 Further reading: Honeypots: What are they? Avoiding them in data gathering

To avoid falling into these traps, you should inspect the HTML code of the website and look for any signs of hidden or deceptive links or elements. You should also use common sense and avoid following links that look irrelevant or suspicious. You can also use tools like Infatica Scraper API that have built-in features to filter out unwanted links or domain crawl your website.

Conclusion

In this guide, you have learned how to crawl a website without getting blocked by following 7 tips. You have learned how to check and follow the robots.txt file of the website, how to use a proxy server and rotate IP addresses frequently, how to use real and diverse user agents and browser headers, and much more. By applying these tips, you have improved your web scraping skills and knowledge, and you are ready to tackle any web scraping challenge. Happy scraping!

Frequently Asked Questions

The robots exclusion protocol (robots.txt) is a file that tells web crawlers which pages or files they can or cannot request from a website. You should follow it to respect the website's rules and avoid getting blocked for violating them. However, some websites may still block you even if you follow the robots.txt file, so you should also use other techniques to crawl a website without getting blocked.

A proxy server is an intermediary between your device and the target website that hides your real IP address and location. Using a proxy server reduces the chances of getting blocked by the website, ensures your anonymity, and allows you to access geo-restricted content. You should choose a reliable proxy service provider and use either datacenter or residential IP proxies, depending on your task.

Rotating IP addresses means changing your proxy IP address after each request or after a certain period of time. This makes you look like different internet users and prevents the website from detecting and blocking your web crawler. You can use a proxy rotator service or choose a proxy provider that offers rotating IPs, such as Oxylabs Residential Proxies.

User agents are strings that identify the browser, operating system, device, and other information about the client that is making the HTTP request. Websites can analyze the user agents of the requests and block those that look suspicious or fake. To avoid this, you should use real user agents that match the browser and device you are using, and change them frequently to avoid detection.

CAPTCHAs are tests that websites use to verify if the requester is human or not. Cloudflare is a service that protects websites from malicious attacks and bots. Honeypot traps are hidden links or elements that web crawlers may follow but humans would not. To overcome these challenges, you can use various methods, such as solving CAPTCHAs automatically with anti-CAPTCHA services, using headless browsers to bypass Cloudflare, and making scripts to avoid honeypot traps.

Sharon Bennett

Sharon Bennett is a networking professional who analyzes various measures of online censorship. She lends her expertise to Infatica to explore how proxies can help to address this problem.

You can also learn more about:

Proxy service demand doubled as businesses recognize the importance of cybersecurity due to new SEC regulations
Proxies and business
Proxy service demand doubled as businesses recognize the importance of cybersecurity due to new SEC regulations

How did new SEC regulations influence proxy service demand? Which search terms are rising in popularity on search engines? Read the latest Infatica's report to learn more.

What Are Proxies for Bots? Everything You Want to Know
Proxies and business
What Are Proxies for Bots? Everything You Want to Know

Learn why proxies are essential for botting sneakers and other online products. Find out the best types of proxies for bots and where to get them.

How Many Proxies Per Task Do I Need?
Proxies and business
How Many Proxies Per Task Do I Need?

Discover how many proxies you need to perform data collection, SEO monitoring, sneaker copping, ad verification, and more.

Get In Touch
Have a question about Infatica? Get in touch with our experts to learn how we can help.