Web scraping is the go-to method for gathering large amounts of data. However, websites today protect their content and take rigorous measures like limiting requests or banning IP addresses to catch bots. This is largely a result of bad bots – they pose a threat to customer information, overloading the servers, among other risks. However, anti-scraping techniques and other measures are a headache to web scrapers and can easily hinder your project’s success when scraping. So, if you’re looking for tips to increase your chances of success, this guide will teach you all about web scraping best practices – from respecting a website’s guidelines to improving your browser fingerprint.
How Do Websites Detect Web Scrapers?
There are several ways websites can identify you:
- Websites use cookies – a piece of data saved to your web browser. Cookies store information related to your actions on a website. This way, web admins can track information about your device or preferences.
- An IP address is another identifier. It includes your location data and other information like your internet service provider.
- And third – the hardest to combat – is your browser’s fingerprint. It combines dozens of software and hardware parameters. Various fingerprinting methods allow web owners to catch scrapers using identifiers like the user agent you send with the request.
Web Scraping Best Practices
Now, let’s look at the web scraping best practices so that you can avoid websites identifying your activities as bot-like.
1. Respect the Website’s Guidelines
Websites have instructions that need to be followed. You might get an IP address ban if you don’t comply with them. There are two major guidelines to look at:
- robots.txt. It’s a set of instructions for managing bot traffic. The file specifies what pages can or cannot be scraped and how often you can do so.
- Terms of Service. Every website has its Terms of Service (ToS), which functions as a contract created by the website. By agreeing to these terms, you’re legally bound to adhere to the specified rules and conditions outlined in TOS.
2. Consider Privacy and Legal Endeavours
In essence, the process of web scraping is legal, but it raises many ethical concerns. That’s why you should be aware of a few things while gathering data.
Scraping personal information is out of the question. Don’t collect data that’s behind a login because scraping public data is a legal violation. And even if the data is public, some information is protected by copyright or other laws.
Remember that each case is different, so you should consult a lawyer if you’re unsure.
3. Don’t Overload the Server
The process of web scraping often involves running hundreds of concurring requests. Even larger websites may find it taxing if many scrapers tackle them at once. Not to mention smaller websites that don’t have enough resources to handle such a load. This could crash their servers.
This is why you should be polite and add delays between your requests, don’t scrape during peak hours, and be considerate overall.
4. Use Residential Proxies
In most cases, you won’t be able to get many successful requests without residential proxies. Here’s why.
A few years back, websites didn’t have such strong anti-bot mechanisms. You could have easily scraped a website using datacenter proxies. But today, these IP addresses are easy to detect since they’re held in servers of cloud hosting companies like Amazon AWS. These proxies don’t rotate by themselves – you have set up proxy rotation by yourself or use specialized tools.
A residential IP address, on the other hand, comes from real user devices and rotates by default. This way, it’s harder for websites to block you since your address will appear as belonging to a different person. So, make sure to get the best residential proxy provider to reach better results.
5. Use a Headless Browser with Dynamic Websites
Modern websites use JavaScript elements to display content. You know when you’re scrolling through social media or news platforms, and the content never ends? That’s called endless scrolling; regular HTML extraction tools don’t help here.
Websites check if your browser can render JavaScript to see whether the request is coming from a real one. A headless browser can fully load dynamic content while mimicking user behavior and hiding digital fingerprints.
Popular headless browser library examples are Selenium, Puppeteer, and Playwright. Remember that if a website doesn’t use dynamic elements to load content, you don’t need a headless browser, and regular libraries like Requests and Beautiful Soup are better for the job.
6. Improve Your Browser’s Fingerprint
Every connection request to a website contains headers that show information about your device. You should pay particular attention to one header – the user-agent string. Let’s see why.
It holds information about your operating system, timezone, and other parameters. The target website can block your request if the string is missing or malformed. For example, a popular Python library, Requests, sends its user-agent header, so you need to change it to one of the popular browsers.
However, using the same user agent also poses problems because websites track requests that come from the same browser. Another tip is to gather a list of user agents and rotate them. Keep in mind that the headers should be up-to-date.
7. Take Care of Your Web Scraper
When you subscribe to a web scraping service, the provider takes care of both your scraper and proxy management. But if you’re building a tool yourself, you need to make sure that it doesn’t break.
Why should it? For example, a website may change the HTML structure, so your code might not work anymore, or add new anti-scraping measures to break your scrape. This can impact your scraper’s functionality. To avoid this, you need to adjust the code accordingly.
The scraper can also break because of the components it includes. Let’s say you’re using proxies, and the server goes down. The scraper will snap, and you’ll need to fix the issue.
8. Act Human-Like
This is as simple as it gets – your scraper should act like you would. Real user actions are much slower and unpredictable, while bots are programmed to use specific patterns.
To trick the website into thinking your bot is a real person, change time intervals between your requests, include random mouse movements, or click specific elements on the page. In essence, you should be as unpredictable as you can.
Featured image provided by Markus Spiske; Pexels; Thanks!
