6 Tips for Building an Effective Web Scraper

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web scraping

Web Scraping is, hands-down, one of the best ways to get data from websites without having to get access to the website’s database or APIs. Web scrapers, also referred to as web crawlers or web spiders, perform queries automatically and at a higher speed compared to doing it manually, allowing you to save time and money. 

When building a web scraper, you have to ensure that it performs well and is capable of delivering quality results for a long period. To make that possible, you have to pay attention to factors such as the kind of data that you want to get and where you want to get it from. 

If, for example, you want to collect data from sophisticated websites, you would have to build a more sophisticated scraper to get the job done. Whatever your goal, the following tips should guide you in building a scraper that will deliver the right results:

1. Get the right framework

The framework that you choose can go a long way towards determining the longevity as well as the flexibility of your scrapers. To ensure maximum flexibility and an increased survival rate of your scrapers, you should aim to build your scrapers on an open-source framework. 

The most popular framework currently is Scrapy, even though there are lots of amazing options depending on the language and OS that you use. Python is largely preferred due to its versatility, but if the site you are targeting is quite complicated to access, you can use special Javascript tools for maximum effectiveness. 

2. Use a unique crawling pattern

The main reason why some web scrapers are not effective in their functionality is that they use almost similar patterns, making them easy to detect and block. To prevent being blocked by sites that have anti-crawling mechanisms, you should consider programming your web scraper using a crawling pattern that is different from others. 

3. Send requests via proxies while rotating them as needed

Your IP address is usually visible when scraping. As such, the target site can use data such as user patterns to know what you are doing, hence determine if your main aim is to collect data. When using the same IP address to send multiple requests, there is a high probability that you will get blocked at some point.

That is why you should use rotating proxies for web scraping, as they make it harder for the target website to get the details of the original IP, reducing your chances of getting blocked. There are various methods that you can use to change your outgoing IP addresses, such as VPNs, Proxies, and TOR.

4. Use different User Agents and HTTP Request Headers for requests

A user agent is a tool that informs a server about the web browser that you are using. Without a user agent, you will not be allowed to access the content that is on a particular website. As you can expect, using the same user-agent header for all your requests will result in the detection of the web scraper as a bot.

Since the majority of web scrapers do not contain a User-Agent by default, you will have to add it yourself. The most important part of adding the user agents is to ensure that you always change the Agents and the corresponding HTTP request headers regularly.  

5. Adjust your scrapers regularly

When building your scrapers, you should also pay attention to how easy it is to change how they work when you need to. That is in consideration that websites are changing and evolving all the time, and so should your scrapers. You will not benefit much from a scraper that uses rigid logic, since it may give outdated information when a site undergoes a major transformation. 

In a worst-case scenario, the scraper can as well crash, and leave you stranded. As such, you should aim to update your scrapers as often as possible to ensure that they are always providing accurate information. 

6. Think about storage

When building web scrapers, it can be quite easy to forget about your Storage needs. You have to get a ready storage solution to avoid being stranded when your data starts streaming in. If you are not expecting a lot of data or you are just starting, a spreadsheet should come in handy, but you will have to move to other practical solutions such as databases as your data increases in size.

For large data sizes, a NoSQL database should be a good choice. The location of actual storage can vary from a normal server to cloud storage. Whatever the situation, always ensure that you have the right plan for storage. 

Final thought

With the tips mentioned in this article, you should be in a better position to build a web scraper or crawler that will get you the data that you need. If you ever feel stuck when building your web scrapers, you can always seek assistance from an expert, for the best results.



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