HTTP headers are extra pieces of information that are sent along with a request or response using the HTTP protocol. The purpose of these headers is to provide more details about the information being sent, such as what kind of data it is and what language it’s in.
Each HTTP header comprises a case-sensitive name (like user-agent, referrer, cookie) and a colon (:) followed by its value.
What are HTTP Headers Used For in Web Scraping?
In web scraping, we use HTTP headers to mimic a user’s behavior. When you go to a website, your browser sends a request with specific headers to identify itself and to tell the server how to handle that request. We can tell our script to do the same
For example, when I go to www.scraperapi.com, my browser sends the following user-agent:
user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36 Edg/109.0.1518.52
However, when we send a request from a script (for example, using Requests in Python)
import requests
url = 'https://httpbin.org/headers'
response = requests.get(url)
print(response.text)
… here’s the user-agent header the target website is getting:
user-agent: python-requests/2.27.1
The server will have no problem identifying and blocking our scrapers with this user-agent, so changing it to a more natural set of headers will give us a better chance of scaling our data pipelines
Because we understand how this works, ScraperAPI uses statistical analysis, machine learning, and browser farms to choose the best set of HTTP headers to send along with your requests, ensuring you have access to the data you need.
You can learn how to use custom headers in our guide or try ScraperAPI for free to test how it works.
Learn more
- Build a web scraper using Python (beginner-friendly walkthrough)
- Understand what’s a proxy and how they work
- Learn how to hide your IP effectively for web scraping
- More frequently asked questions about web scraping and data extraction
