What to look for in a web scraping API?

There are various web scraping services available, each offering distinct features. But what exactly should we look for in a web scraper API 🤔?

To cut it short, the best web scraping API differs based on the use case and, of course, the target website. Here are five core features you should consider when looking into one.

Headless browser support

Most websites nowadays rely on JavaScript in their front end. This allows for smooth website navigation when using a web browser. But from the web scraping perspective, it only adds further complexity!

This is because plain HTTP requests cannot execute JavaScript, preventing data rendering data on dynamic websites.

Therefore, a reliable web scraping API should support headless browsers like Selenium to enable data extraction on such such target web pages.

Pro tip 😉: Disable JavaScript from the browser developer tools to determine whether JavaScript is required for your web scraper. This will allow you to know what a regular HTTP request can see.

Full browser control support

Reaching a certain web page isn't always as easy as sending a simple request. Instead, a request must often follow particular steps till the final source, such as:

• Scrolling infinite pages to load more data.
• Clicking buttons and filling in elements.
• Searching for keywords and filtering data.

Some of the above actions can be executed using query parameters or private website APIs that run in the background. However, other actions can be challenging to replicate without browser interactions. For example, adding items to a cart on an e-commerce app for shipping data.

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Most web scraping services provide browser automation essentials, such as executing JavaScript code or taking screenshots. However, they differ in the remaining supported headless browser features, such as:

• Auto-scroll actions.
• Taking screenshots.
• Native mouse and keyboard clicks.
• Rendering waits and waiting for selectors.

A web scraping API with full browser control is necessary for scraping data from complex web pages. It doesn't have to support all the headless browser features, but the major ones are necessary.

Auto Parsing

It's known that parsing is one of the main challenges of modern web scraping. This is due to a couple of reasons:

• Comprehensive HTML page sources with confusing tag details.
• HTML is continuously updated, making the parsing selectors obsolete.

Because of the above limitations, many web scraper APIs auto-parse HTML pages on specific websites. which return the page details as a clean JSON document.

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A web scraping service with auto-parsing capabilities can save time and effort by eliminating the need for manual CSS or XPath selector development. However, poor parsing logic maintenance can lead to several issues for the following reasons:

• Parsing logic can quickly expire, leading to empty fields.
• Localized website pages can have different HTML sources, making the selectors invalid. This is commonly encountered when using proxies in a different geolocation.

Web scraping speed

The request-response lifecycle speed is another essential metric when looking for a web scraping service, especially when scraping in real time.

It's known that sending a request through a web scraper API takes more time than using HTTP clients directly. This can happen due to some reasons:

• Forwarding the request to the API and then to the target website is prone to network performance, adding potential latency.
• The web scraping API can utilize fine-tuning and retrying logic
• If JavaScript is enabled, fully loading the page content, including its background requests, can be time-consuming.

The speed of an API scraper can differ depending on the target website. Therefore, it is important to evaluate the speed of web scraping services against the same target website to get accurate results.

Success rate & stability

Finally, success rate and reliability are arguably the most critical metrics when looking at an API for web scraping.

Success rate

The success rate is the ratio of successful requests to the total number of requests. Such a ratio can be affected by all non-succssful requests. Though, it's important to only consider the blocking status codes (403, 429, etc.). As other failures can be affected by the target website itself, such as expired pages or internal errors.

When looking at the success rate of a web scraping API, it's essential to consider the number and types of the evaluated URLs. This helps prevent false positives, as the success rate can vary on different routes.

Check out our benchmarks table for success rate comparisons of the most popular web scraping targets.

Reliability

The reliability of an API for scraping is a crucial metric that's often overlooked.

A web scraping service can have an exceptional success rate, but is this success rate sustainable? Anti-bot services are continuously updated and patched with the discovered leaks or potential flaws. Hence, a maintained web scrapinsg service can have a better success rate in the long run.

Another reliability factor to consider is the types of failed requests. Web scraping already deals with uncontrollable factors, including network issues and parsing errors. Additional internal errors would reduce the overall succes rate.

Keeping an eye on those failures and their rate is the key to ensuring a reliable web scraper.

Summary

A web scraping API can notably improve the data extraction process. We went through the core features to consider when looking into one:

• Headless browser support for scraping dynamic pages.
• Browser control support for automating web page navigation.
• Auto parsing to retrieve the HTML data directly in JSON.
• Web scraping speed, especially when scraping in real-time.
• Success rate of the service and how sustainable this rate is.

Looking for the above metrics? They can be found in our services benchmark table and the web scraping APIs overview.