Website Parsing: An Inside Look

It is also worth considering the robots.txt file, which contains instructions for search engines such as Google and Yandex. If the site owner has set restrictions on crawling certain pages, ignoring these instructions may be unlawful and inappropriate.

3. Parsing using requests and BeautifulSoup

One of the simplest and most common ways to parse HTML pages is to use the Python libraries: requests to make HTTP requests and BeautifulSoup to parse HTML code.

• A GET request is sent to the specified URL;

• Getting the HTML code of the page;

• Uses a BeautifulSoup object to find and extract the desired data from the HTML code.

This example demonstrates a basic approach to web scraping using the Python requests and BeautifulSoup libraries. However, parsing can be more difficult in the case of pages with dynamic content or nested structure. In such cases, additional data processing may be required to extract the necessary information.

4. Static pages

Static web pages are web pages whose content remains the same regardless of user actions or time. This means that every time a page is requested, the server serves the same HTML code without any additional processing or changes.

Static web pages can be easily parsed using HTTP request tools (such as Python's requests library) and HTML parsing tools (such as BeautifulSoup). This allows you to extract data from web pages for further analysis or use.

5. Dynamic pages

Dynamic web pages are web pages that can change their content without reloading the entire page. This is achieved through the use of technologies such as JavaScript and AJAX (Asynchronous JavaScript and XML), which allow the page to communicate with the server and update content on the fly.

For example, online stores with an endless feed, where you need to scroll the page to download “cards.” This is a typical example of dynamically loading data as you scroll a page, which is often used to optimize performance.

Dynamic web pages are often used to develop interactive web applications, social networks, online stores and other web services where it is important to provide users with fast and easy navigation and interaction with content.

6. Working with API

If parsing static pages is quite simple, then working through the API will help with dynamic ones.

• Open APIs provide access to site data and functionality for use by other programs or applications. They may be paid or have some restrictions on the number of requests or features available. An example of an open API would be an exchange API that provides information on stock prices and other financial data;

• Hidden APIs are not intended for general public use, but can be discovered and exploited through network traffic analysis. This can be a more complex and technically demanding process, but in certain cases it may be the only way to obtain the necessary data.

7. Protection from parsers

Take a look at the comment:
“We are not going to sue anyone for a piece of text, we’ll just make it as difficult as possible for similar services and programs for downloading sites. These services will receive 404 on almost all pages. Anything we want to send externally, we will give through the API.”

When website owners want to protect their content from automated downloading or scraping, they can use various methods and techniques to make it difficult or prevent such actions. Here are some of them:

• User-Agent filtering. Web servers can check the User-Agent in HTTP requests and block requests from known bots and scripts. Therefore, it is important to use a suitable User-Agent in requests to bypass this protection;

• Limiting the frequency of requests. Web servers may limit the number of requests they accept from a single IP address in a given period of time. This may slow down or stop a parser that sends requests too quickly;

• Using JavaScript to render content. Many websites load content using JavaScript after the main HTML code of the page has loaded. Parsers that cannot handle JavaScript may have difficulty extracting data from such pages;

• Applying CloudFlare protection. Security services like CloudFlare can provide additional protection against scrapers, including CAPTCHA, blocking IP addresses with anomalous behavior, and other protection methods.

8. Ways to bypass protection when parsing websites

• Replacing User-Agent and other headers. Changing the User-Agent and other request headers allows you to hide the parser's identification and emulate requests as if they were sent by a regular browser. Libraries such as fake-useragent provide the ability to generate a random User-Agent for each request, making parser detection more difficult;

• Selenium. Selenium is a web browser automation tool that can be used to emulate user interactions with web pages. It can be effective in bypassing security by allowing JavaScript to be executed and simulating user actions such as filling out forms and clicking links. However, Selenium is resource intensive and can be slow compared to other parsing methods;

• Using proxy servers. Using proxy servers allows you to hide the source IP address of the parser, slows down the speed of requests and reduces the risk of blocking. This allows you to increase the number of requests without attracting the attention of the website being studied;

• Using a pool of IP addresses. For ongoing website scraping, such as tracking product prices on marketplaces, using a pool of IP addresses can be an effective method. This allows you to distribute requests between different IP addresses, which reduces the risk of blocking and increases the reliability of parsing.