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Web Crawler & Spider Development

What is Web Scraping?

Web scraping, also called web crawling or web spidering is using a computer to go out and collect information from a website. This helps you collect a large amount of data in a smaller amount of time, as compared to doing the work by hand. There are a number of different types of web scraping tools and techniques. In general though, the web scraping tool will download webpages, extract information, and save it for later.

How Can I Use Web Scraping?

You can use web scraping in a large number of ways. The most common ways businesses use web scraping (in our experience) is to collect data about other companies. Some common tasks include:

  • monitoring your competitors’ product prices
  • tracking their published employee information on sites like Glassdoor
  • see when other companies are hiring new people
  • track when companies are expanding into new markets
  • create lists of companies to market to
  • analyze companies automatically to find the ones best suited to your B2B marketing campaign, and
  • optimizing your own business processes.

How Does Web Scraping Work?

In general, web scraping follows a 3-step pattern: download, parse, and store. First, the web scraper needs to download a webpage (or other data) from a website server. This can be done using a number of tools, but the cURL library is quite popular. Second, the web scraper needs to extract the desired information from the page it downloaded. In some cases, this isn’t necessary (for some image crawlers, for example), but for the most part, your crawler will need to extract what you want from the data you’ve downloaded. Third, your web crawler needs to store the data you’ve collected and extracted. There are a range of storage options, from databases to files to spreadsheets.

How are Web Crawlers Developed?

At Potent Pages, we develop web crawlers in the following pattern:

  • identify the project requirements and data needed,
  • examine the target site to identify the location of the desired data,
  • write a program to download the desired webpage(s) or data,
  • write a program to extract the desired information from the downloaded pages,
  • store the desired data,
  • and provide the resulting data in the desired format.

The requirements of the project and the types of data being collected will determine what sort of tools and techniques need to be used. In many cases, a general purpose crawler (e.g. a web spider or a tool that just downloads an entire website) with a custom extraction system will provide the most robust solution. In others, a custom downloading tool is required. The best downloading system just depends on the site and what sort of data is needed.

Similarly, the best processing for a web scraper will depend on the structure of the data collected and what needs to be done with the data. In simpler cases, a simple Python or PHP script will be able to extract and process all of the data required. In more complex situations, a more complex program with custom coding is required.

Storing and providing the data will depend on you and how you will need the data. For some applications, a spreadsheet will do well. In others, a database is required. Along the same lines, if you have a small amount of data, you can receive your results in an email. However, if you have a larger quantity of data, you will most likely need to have the data stored on a server for direct download.

How Much Does Web Scraping Cost?

The cost of web scraping can vary depending upon the difficulty of your project. A simple crawler can range anywhere from $100-$400, and more complex crawlers can cost $800 to $1500 or more. There are also tools that will help you do the work yourself for free. The cost just depends on your needs.

Do I Need a Web Scraper?

Whether you need a web scraper or not will largely depend on the type and quantity of data you’re looking to acquire. If you need a large quantity of structured data collected from a website (like numbers, titles, or tables), or even data that’s partially structured (like HTML webpages), web scrapers may be able to help you. However, if you’re dealing with a small amount of data, it’s often easier to just have someone do the work for you. Similarly, for completely unstructured data, like books or the text within webpages, understanding the meaning of the content can often require a person, at least as of 2023. However, technology is continuously advancing, so if you need some help figuring out what to use and how, please contact us using the form below.

I’m a Collector. Can You Monitor Prices For Me? Can You Find the Best Deals?

If you’re a collector and would rather spend your time collecting and less time looking through websites for good deals, we may be able to develop a web crawler to help you with that! We can track auction and e-commerce sites for items that you’re looking for, extract the information, save it to a database, and examine the prices and other attributes to find deals for you. In some cases, we can even build a crawler to go out and automatically buy good deals that pop up.

Is Web Scraping Legal?

The legality of web scraping can vary depending on your location, how you download content from a website, and what you do with the data. While you will need to consult with an attorney regarding your specific needs, in general, you will need to make sure that your spider doesn’t cause any harm to the website’s server, that you follow the website’s robots.txt file, and that you aren’t violating the website owner’s copyright by using their data.

How do I Download a Website?

Once you’ve decided that you want to download a website using a website using a web crawler, there are a number of methods. These range from web spidering on the general end to targeted crawling for focused work. You’ll want more general web spiders if you’re looking to use the entire content of a webpage (such as tracking page titles, links, etc.). If you’re looking to get specific information from a site (such as product information or data), it can be better in some circumstances to build a crawler to target those needs.

What is a Web Spider?

A web spider is a tool that follows links from page to page, downloading and parsing each page along the way. In this way the web “spider” is crawling the internet “web” made up of links, hence the name. This is how search engine spiders, such as Google’s GoogleBot or Bing’s BingBot work. There are a number of tools that will allow you to download entire sites too, with varying degrees of complexity and efficiency. However, the more efficient spiders require more complex coding techniques.

Can A Scraper Send Notifications or Emails to Me?

Absolutely! A well built web scraper, spider, or other crawler can notify you in a number of different ways.

  • If you need to know when there was a successful run or if there was an error, a crawler can be built to send out a text message or email.
  • If you need the crawler to send you a summary of the results of the data, you a web scraper can send you an email with an attachment, or with the data in the body of the email itself.
  • If you need a large amount of data exported, your web crawler can save your data to a file and upload it to a web server. The crawler can then email you a link to the file so you can download it, without clogging up your inbox

The best web scraper for your needs will be able to send you the data in the best format that works for you.

How Can a Web Scraper Send Data To Me?

A well built web scraper can send you your data however works best for you and your situation. Whether you need a spreadsheet (CSV document, XSLX, or something else), a database (MySQL, for example), or in files (compressed or uncompressed), a well built scraper can provide you the data you need in whatever format you’re looking for.

Who Should I Hire to Build a Web Scraper?

Who you should hire to build you a web scraper will depend on the goals of your scraping project. If you need a large amount of data, or need it in any way customized, a custom web crawler programming firm may be best for you. At Potent Pages, this is what we do.

On the other hand, if you need something simpler, like a few dozen webpages downloaded and some content extracted, you could use one of the many automatic tools available, like 80 Legs or If you need help figuring out the best solution to what you need, please contact us using the form below and we would be happy to explain the best crawling options available to you.

Answers to Some Other Questions

I Want to Build a Web Crawler. Where Do I Start?

After you’ve decided to build a web crawler, and know what website you want to crawl for what data, the next step is to start designing and programming your crawler. The difficulty and efficiency of the crawler you use will depend largely on the language you want to use and the complexity of your project. If you’re getting started on your own, we have a list of web crawler tutorials available here. If you need help at any stage of the process, and are looking for professional assistance, please contact us using the form above.

How Fast is My Web Scraper? What Defines the Speed of a Web Scraper?

The speed of a web scraper is generally defined by the number of pages downloaded per time, for example 10000 pages per hour. In general a web scraper’s speed is determined by the delay that the scraper has to wait before it receives a response from the web server. So, for example, if you have an average of a 2s delay between requests, and only parse one page at a time, you’ll end up with a throughput of 1,800 pages per hour. If you can download 100 pages at a time though, you would be able to get that up to 180,000 pages per hour.

What Are XPaths?

XPaths are a way of identifying elements in an HTML document. They are used by web crawlers to navigate through a website and extract specific information repeatedly.

XPaths use a series of expressions to locate elements in a document, such as selecting elements by:

  • their tag name,
  • attribute, or
  • position in the document hierarchy.

Web crawlers use XPath to scrape data from websites, such as product information or contact details, and then store it in a database for later analysis.

How Many Googlebot Crawlers Are There?

There are 19 Googlebot web crawlers. There are 2 main varieties: Googlebot mobile and Googlebot desktop. These 2 main crawlers are then used for the 19 Googlebot crawlers.

Looking to download a site or multiple webpages? Interested in examining all of the titles and descriptions for a site? We created a quick tutorial on building a script to do this in PHP. Learn how to download webpages and follow links to download an entire website.

Looking to automatically download webpages? Here's how to download a page using PHP and cURL.

In this tutorial, we create a PHP website spider that uses the robots.txt file to know which pages we're allowed to download. We continue from our previous tutorials to create a robust web spider and expand on it to check for download crawling permissions.

Looking for some quick code to build your web crawler in PHP? Here's some code we use a lot here at Potent Pages to make our development a lot easier!

Tired of your web crawlers getting blocked? Try using a free proxy. In this article we explain what proxies are, how to use them, and where to get them.

While web crawlers can be useful and even necessary in some cases, using them can also raise significant legal concerns.

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Discover the power of XPaths for web crawling and data extraction in this expert guide. Learn how to write effective XPaths with real-world examples.

Discover the true cost of a web crawler for your business needs. From open-source to commercial solutions, find the best fit and ROI for your budget.

Wondering how many Googlebot crawlers there are? Google has 19 Googlebot web crawlers. What Are Google’s Web Crawlers? Here’s an • Read More »

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