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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? In the realm of web development, it's common to create a web scraper using JavaScript and Node.js due to their efficiency in handling asynchronous tasks. This approach enables rapid data retrieval from numerous sources simultaneously. By properly setting a User-Agent in your requests, you respect server constraints while effectively collecting data.

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.

CAPTCHAs are tests put in place to tell humans and robots apart. As a user who has experienced CAPTCHA in action, you no doubt know just how frustrating it can be. To avoid any of these issues, it is better to add User Agents to your web scraping strategy.

You now know what UAs are and why they are important for web scraping. But is that all you need to know about User-Agents? Of course not! Below is a guide to help you as a user, make full use of User Agents for your Web Scraping.

How to use User-Agents for Web Scraping

User-Agents - Meaning and Importance in Web Scraping

During your web scraping, a wrong move can end up with a ban on your UA by webservers. Hence, it is not enough to just simply add User Agents to your web scraping strategy. You have to know how to fully utilize them to help you get the best results and avoid any problems. The following will help you in this aspect.

1.) Switching User Agents

As seen above, sending requests without a UA will get web servers suspicious. In the same way, using a particular UA for several requests will also raise their suspicion. As a countermeasure, the destination server will block that User-Agent. But fortunately, you can avoid this. How?

Consider Proxies (another effective tool for internet scraping). Proxies are servers that possess an IP address. Hence, when you switch them, you are changing IP addresses making the destination server believe its traffic is from different users. The same applies to User Agents. By using different UAs for different requests, a web server won't suspect the presence of a bot.

Switching between or rotating UAs may sound challenging. Rest assured, it is easy to do so. You only need to get lists of UA strings.

When doing so, ensure your strings are from real internet browsers. You can find a variety of these strings at

Next, store the strings in a list in Python. Afterward, you can set each request to randomly select a User-Agent from that list.

Thankfully, the net swarms with lots of materials to help you perform User-Agent rotation with ease.

2.) Select a common UA

Down to our second tip - select common User Agents. Why? If your User Agent does not belong to a major web browser, web servers will get suspicious. And as we've seen throughout this article, whenever a server gets suspicious, it may lead to your UA getting blocked.

Hence, to avoid this, you need a User-Agent that is commonly used. Here are some User Agents that belong to common web browsers.

  • Google Chrome

Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36

  • Microsoft Internet Explorer 7 / IE 7

Mozilla/5.0 (Windows; U; MSIE 7.0; Windows NT 6.0; en-US)

  • Mozilla Firefox

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:53.0) Gecko/20100101 Firefox/53.0.

You can find more of these User Agents at

Note that when selecting UAs, choose one that suits the browser you're using for your scraping. This is to ensure that the browser matches the default behavior of your User-Agent. And in turn, this will help you achieve better results.

Uses of web scraping

Uses of web scraping

As seen above, web scraping offers lots of benefits to users. Let's see in detail, some areas where web scraping is helpful.

Data Analysis

Data analysis is an essential process that all businesses make effort to take. It involves interpreting, organizing, or as the name implies, analyzing data to derive helpful information. This info can be used to draft marketing strategies and so on.

But first and foremost, data analysis involves collecting data from the web. And this is where web scraping comes into play. To easily extract data from the net, data analysts ensure to add web scraping to their skill set.

Generating Leads

Information for cold outreach such as email addresses and phone lists can be gotten via scraping. Thus, web scraping helps in building leads for businesses.

Used in monitoring competitions

As a brand, it is necessary to keep track of your competition. This is a simple but effective strategy in the business world. By comparing their products and prices with yours, you may be able to ascertain where and how to improve. Web scraping will help you extract any data you need for monitoring your competition.

Wrapping Up

Though User-Agents are not a must-have tool for web scraping, implementing them is the best way to avoid any complications. After all, you don't want to wound up trying to get rid of an annoying CAPTCHA.

True, web scrapers have advanced over the years. But the same is true for anti-scraping technologies. And that's yet another reason that calls for the need for a User-Agent library. By selecting common User Agents and rotating them, there is no doubt that you'll achieve a smooth web scraping experience. So, as a user (both beginners and experts alike), you may want to opt for User Agents.


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