User-Agents For Web Scraping 101

It is no secret that the net swarms with tons of information. And extracting this information has become the lifeline of many online businesses today. As a result, web scraping remains a powerful process in the data world.

Simply put, web scraping refers to a process of extracting data from sites and converting it into useful formats. Through web scraping tools (bots), one can easily access any needed data from various websites.

The data extracted from web scraping offers lots of benefits, especially to digital businesses. From price comparisons to lead generation, as a brand, you will no doubt benefit from this method. And as a user, web scraping can help you in your marketing, scientific, or even academic research.

Aside from bots, other tools greatly aid the web scraping process. One of which is User Agents. As a professional in the web scraping field, you may understand the importance of implementing User-Agents in your scraping. But as a beginner, you may wonder what User-Agents are, why they are necessary, and how to use them. Not to worry, this article answers those questions.


User-Agents - Meaning and Importance in Web Scraping

User Agents typically follow this pattern:

Mozilla/5.0 (<system-information>) <platform> (<platform-details>) <extensions>

With that in mind, here's an example of an iPad's UA:

Mozilla/5.0 (iPad; CPU OS 8_4_1 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Version/8.0 Mobile/12H321 Safari/600.1.4

Thankfully, the Mozilla developer website gives a full overview of a User Agent's characteristics.

From the above definition and template, you'll see that a UA contains all info required by web servers to respond to requests. How?

Well, this brings us to our next question: Why are User Agents important? UAs are beneficial to both you, as a user, and the destination web server.

First, to the destination server: Web browsers often send your User-Agent through headers of your requests. Hence, each time you make a request, your UA is also sent to the destination server. As seen above, the server uses the data from your UA to ascertain your browser, OS, and device. Using this info, the server can provide a response that matches your details.

For instance, when you visit a site on your PC (Windows), the site provides you with its desktop version. Now, try visiting that same site with your phone (Android). No doubt, you have a mobile version of the site. How does the website know which version to present to you? The answer lies within your UA.

Next, to the user: Consider the above definition once again. UAs are strings of texts. As such, it isn't difficult to change it, thereby tricking web servers into believing they are getting traffic from different users across different devices. And this makes it a very effective tool for web scraping. How so?

Web scrapers often send your request without a UA. Since there is no info about the user, the destination server may suspect that a robot is in play. And this can result in CAPTCHAs.