Browser, server and your computer need to process a number of actions to give a result for any of your requests in a search bar. User agent comes as an essential part of this process. Without this technology, your browser won’t be able to communicate with sites. In data harvesting projects, user agents also play an important and in some case major role. Overall quality of scraping highly depends on the user agent’s rotation. In this article, we will discuss all the important details about user agents in the context of web scraping.
What is a User Agent?
User agents are usually connected to the process of creating a link among the user system and website. In other words, a user agent is a part of a technology that provides users with a connection to the Internet. Usually, the user agent looks like a text that describes the identification details of your device. That includes details about the operating system and browser you are using.
Browsers are forced to apply data from user agents every time for communicating with sites or pages on the Internet. Information in the user agents mainly serves as the introduction of your system for the server. Based on this data server can adjust content or form of the page, so all the browsers have a unique user agent that correlates with them.
User agent string, or simply UA strings, can specify for the server that you are using a Firefox browser in Windows 11 system. The server needs this data to form an answer that will correspond to all this information. Certain parts of the UA content can be guided by the user itself, but other details controlled only by the sites. Search engine crawlers, for example, do this kind of work automatically.
Reasons for User Agent Spoofing
With the help of the UA, the server can automatically identify what kind of device is trying to get a connection. This way a server can tell apart a browser, scraper, spambot and other tools. With this ability, almost every site that wants protection for scraping with Java or other tools can activate antibot protection and ban scraping based on the UA.
Scrapers and other bot-like tools can generate fake user agents for scraping. This way web sites and servers will treat scrapers like a legitimate PC. Method of changing real UA to a fake one called user agent spoofing. But, this method can only help in case of scraping from sites with antibot software built in.
How to Avoid User Agent Blocking
To dodge blocking and other troubles, you can try to use a set of valid user agents for scraping. This can help to protect your scraper from blocking in sites that treat any non-popular UA like a potential bot. Without additional setup, most of the data harvesting tools can skip this step and attract more risk of ban.
You can overcome problems of this kind with additional preparations like developing a list of UA and establishing a private proxy connection for your scraper. In this article, we will show some of the most popular examples for UA related to PCs. You can use them to compile your own list to rotate it while scraping. Ultimately, it is better to use UA similar or close to UA of your actual browser to look more like a legitimate PC in the eyes of a server.
With a big number of queries from your scraping program, it is important to randomize your interactions with the server. You can find a fairly simple solution to this problem in changing your real IP address with static residential proxies. With proxies for web scraping, you can send new requests to avoid most of the blocking threats. From the server side, these actions will look like different queries from new PCs.
How to Change the User Agent
Sites can receive hundreds of requests from users every day. If the server behind this site starts to receive numerous queries that look alike from one UA, most likely this UA will be banned. This is a main reason why data harvesting projects need to alter the UA constantly.
One of the ways of dealing with this problem can be in changing your UA to a search engine one. Usually, sites tend to look for better ranks in search results. So, your scraper with the search engine UA in some cases can pass the check and avoid a ban only for that reason.
However, for large harvesting data projects, the best UA will be the one belonging to any popular browser. To alter the scraper UA in a request library, you need to copy UA sting from popular browsers like Firefox or Chrome. Later, you can integrate it into your code with a “user-agent” key.
To test your project UA in the field, try to send a command to HTTP Bin. From time to time, for more consistent work of scraper, you may need to add the headers like Dnt or Accept-Language to your code.
How to Alternate User Agents
However, even if you manage to avoid a ban and learn how to successfully spoof UA, you can face another set of problems. Servers are able to track your operations based on amounts of data you are receiving in a minute. The most simple way to prevent this will be in utilizing a datacenter rotating proxy and the prepared list of a real UA.
To start using different user agents for web scraping, you need to make a list of the real UA from the most popular browsers. With this list on hand, try to create a Python list and program your tool for scraping to use it as a pool for further work. After this, you can add proxies and replace your IP to make it better for web scraping.
You need to remember that rotating of a UA should also include changing of the headers attached to it. Repeat the steps from this paragraph every time you start collecting data to prevent blocking your scraper. You can practice all of these skills on specially created websites to practice web scraping.
List of User Agents for Parsing
Most of the phones, browsers and other software will have a unique UA that correlates with them. You can try to use different sets of UA depending on your data parsing tasks. For example, you can make a list only from UA for mobile devices or only from the search engine ones. In this article we will point out only the user agents for scraping and emulating different browsers for PC:
- Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36
- Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:53.0) Gecko/20100101 Firefox/53.0
- Mozilla/5.0 (X11; CrOS x86_64 8172.45.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.64 Safari/537.36
- Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:15.0) Gecko/20100101 Firefox/15.0.1
- Microsoft Internet Explorer 9 / IE 9: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0; Trident/5.0)
Success of your data harvesting project depends on many things and UA is definitely one of them. For maintaining your scraping over a long time, you need to take care of spoofing UA and changing IP in the process.When you start a new project for data harvesting, make sure that you use the right UA with the right header. It is good practice to keep a list of your headers always organized, so websites with advanced antibot won’t detect you. Also, don’t keep cookies of sites that you’re scraping or login into to avoid being banned. Additionally, if you buy residential proxies, your work with web scrapers can become even easier.
Frequently Asked Questions
Please read our Documentation if you have questions that are not listed below.
What is a user agent?
User agent is a line of text that helps your system connect to websites. User agents contain data about your system and browser that you are using. Website servers adjust content of the pages based on this information.
What proxies are the best for web scraping while rotating user agents?
Depending on your task, the choice of proxies for web scraping can vary. For example, you can try to use datacenter proxy and get a fast and reliable way of changing your IP in scraping projects.
Why should you change user agent when web scraping?
User agents carry information about your system. This way, when web scraping, the server can detect your activity and block your access to the site. Without change of user agents, you will always face blocking of your scraping activity.
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