While web scraping primarily involves the extraction of data from third-party websites, its purpose, and the lengths that websites will go to block your best efforts, is another matter. It’s an extensive process that involves parsing the HTML code from a website and turning it into structured data you can use.
However, as you’re likely aware, this practice is most effective when conducted anonymously, if not unbeknownst to the target website. Scraping can help you glean effective tactics and techniques from competitors, generate leads, and monitor price fluctuations, but acquiring the data can be difficult – here are ten ways to keep the data flowing.
1. Add delays between each request
Slowing down the scraping is an intelligent way to do it. Automated scraping bots work faster than humans. Software deployed to counter web scrapers can recognize such speeds to be those of a non-human visitor.
Avoid sending too many requests to a website within a short period. Space them out. Your web scraper needs to imitate human behavior to give you the best chance of acquiring all the data you need and remain undetected.
2. Switch user-agents
Websites can identify users accessing them in several ways. Every request sent to a website server has a header. The web server can attach a request to an OS, browser, or device through a request header. Using the same user agent for many requests may lead to getting blocked.
So, it is vital to change your user agent often to get past blocks and continue browsing as usual. Create many user agents and enable automatic switching from one to another. Your requests will be untraceable, possibly even undetectable.
3. Use a headless browser
It is easy for a website to attach a request to a real user in today’s sophisticated tech world. It is easy to identify and define a request using its fonts, cookies, or extensions. And, of course, websites can also identify browsers, thus enabling the detection of scrapers.
The best way to get around this is by deploying a headless custom browser. A headless browser protects fonts, cookies, and other personally identifiable information. Thus, websites will receive your requests but not attach them to you or your device.
4. Use proxy servers
Websites have deployed scraper detectors to help them identify and block suspicious activity. Your IP will get blocked if it appears to be sending too many requests to a website, meaning you can no longer access the desired data.
One of the best pre-emptive measures that you can employ is a proxy. Proxy servers alter your IP address, then use the altered one to send requests. It ensures websites do not link requests to your device, even though they may still notice the activity.
5. Scrape from Google cache
Another technique is scraping website data out of Google’s cached copy. Your request to a website only gets blocked if you’re accessing it directly. Scraping out of Google’s data copy changes how you’re accessing the websites.
It works best when a site contains a lot of information. Although it isn’t a foolproof technique, it works for most sites. Many websites with non-sensitive content do not have measures in place to counter this technique.
6. Set a referrer
Setting a referrer header informs a website about the source of an arriving request before it allows it through or blocks it. To obscure your own identity, you can change your referrer header to show Google as the request source.
It is also possible to alter your referrer header according to country. You can gain access to a US site, even though the site blocks requests from the US, by adjusting your referrer header to appear as if the request is from a non-US originating source.
7. Be careful of honeypot traps
Honeypot traps are common for websites that want to block web scrapers. A honeypot is a link in HTML format and is readable by web scrapers, but not by humans. Websites know how attractive honeypots are to web scrapers and purposely set these traps to identify and block them.
When a web scraper reads a honeypot, it has exposed itself as a non-human attempting to access the site via a specific IP address. Any other requests from that IP address will be auto-blocked. So, to continue your web-crawling activities, you’ll need to find ways around these traps.
Websites fiddle with visibility and display when using these traps. They add a link on a page and set its font color similar to the background color. You need to write your web scraping code and configure it accordingly to detect such tricks.
8. Extract data using different logic
Software studies patterns in requests and classifies them as human or not human. Human requests are inconsistent with a more zigzag-like type of browsing. Web scrapers have a consistent browsing pattern that is easy to identify.
Software blocks requests from an IP that displays this kind of consistency. However, it is possible to lead the software to accept a request as one submitted by a human. By adding random clicks on different pages, this technique can sometimes get past software blocking.
9. Set alternative request headers
Websites often block scrapers because of request headers that appear similar. If you are using a web scraper, you need to avoid using titles that websites can recognize. You can pick various headers online and use them to navigate websites, giving your browser a more innocuous look.
You will also need many request headers to survive blocks. Using the same header for many requests is not advisable. Rotate through a series of headers to remain undetectable. You can check for titles online and always aim for headers from the latest updates. Outdated headers can also expose your request and identity.
10. Use a CAPTCHA-solving service
Another technique that you can use is deploying a CAPTCHA -solving service. Websites detect and block web crawlers by displaying a CAPTCHA. Humans can read and solve Captchas, but web scrapers cannot, of course.
Auto-resolving CAPTCHA is a timely and affordable technology that can prove useful–but only to a certain extent. Many website owners are advancing to CAPTCHA that an automatic service cannot solve. The good news is that you can avoid CAPTCHAs altogether.
Undetectable proxies and residential IPs are a few effective alternatives that you can explore to prevent the occurrence of CAPTCHA.
Yes, you can gain uncensored access and extract proprietary data from target websites, but it’s a daunting challenge these days. Websites have become increasingly adept at detecting, blocking, and blacklisting web-scraping bots.
However, no website can completely prevent scraping. You can do it if you follow the correct steps and employ the tips described above. Software tools and the right practices can get you the data you need to compete.
Photograph by Soulful Pizza