How To Crawl Data

Best 3 Ways to Crawl Data from a Website | Octoparse

The need for crawling web data has become larger in the past few years. The data crawled can be used for evaluation or prediction in different fields. Here, I’d like to talk about 3 methods we can adopt to crawl data from a website.
1. Use Website APIs
Many large social media websites, like Facebook, Twitter, Instagram, StackOverflow provide APIs for users to access their data. Sometimes, you can choose the official APIs to get structured data. As the Facebook Graph API shows below, you need to choose fields you make the query, then order data, do the URL Lookup, make requests and etc. To learn more, you can refer to
2. Build your own crawler
However, not all websites provide users with APIs. Certain websites refuse to provide any public APIs because of technical limit or other reasons. Someone may propose RSS feeds, but because they put a limit on their use, I will not suggest or make further comments on it. In this case, what I want to discuss is that we can build a crawler on our own to deal with this situation.
How does a crawler work? A crawler, put it another way, is a method to generate a list of URLs that you can feed through your extractor. The crawlers can be defined as tools to find the URLs. You first give the crawler a webpage to start, and they will follow all these links on that page. Then this process will keep going on in a loop.
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Then, we can proceed with building our own crawler. It’s known that Python is an open-source programming language, and you can find many useful functional libraries. Here, I suggest the BeautifulSoup (Python Library) for the reason that it is easier to work with and possesses many intuitive characters. More exactly, I will utilize two Python modules to crawl the data.
BeautifulSoup does not fetch the web page for us. That’s why I use urllib2 to combine with the BeautifulSoup library. Then, we need to deal with HTML tags to find all the links within page’s tags and the right table. After that, iterate through each row (tr) and then assign each element of tr (td) to a variable and append it to a list. Let’s first look at the HTML structure of the table (I am not going to extract information for table heading

).
By taking this approach, your crawler is customized. It can deal with certain difficulties met in the API extraction. You can use the proxy to prevent it from being blocked by some websites and etc. The whole process is within your control. This method should make sense for people with coding skills. The data frame you crawled should be like the figure below.
3. Take advantage of ready-to-use crawler tools
However, to crawl a website on your own by programming may be time-consuming. For people without any coding skills, this would be a hard task. Therefore, I’d like to introduce some crawler tools.
Octoparse
Octoparse is a powerful visual windows-based web data crawler. It is really easy for users to grasp this tool with its simple and friendly user interface. To use it, you need to download this application on your local desktop.
As the figure shown below, you can click-and-drag the blocks in the Workflow Designer pane to customize your own task. Octoparse provides two editions of crawling service subscription plans – the Free Edition and Paid Edition. Both can satisfy the basic scraping or crawling needs of users. With the Free Edition, you can run your tasks on the local side.
If you switch your free edition to a Paid Edition, you can use the Cloud-based service by uploading your tasks to the Cloud Platform. 6 to 14 cloud servers will run your tasks simultaneously with a higher speed and crawl in a larger scale. Plus, you can automate your data extraction leaving without a trace using Octoparse’s anonymous proxy feature that could rotate tons of IPs, which will prevent you from being blocked by certain websites. Here’s a video introducing Octoparse Cloud Extraction.
Octoparse also provides API to connect your system to your scraped data in real-time. You can either import the Octoparse data into your own database or use the API to require access to your account’s data. After you finish the configuration of the task, you can export data into various formats, like CSV, Excel, HTML, TXT, and database (MySQL, SQL Server, and Oracle).
is also known as a web crawler covering all different levels of crawling needs. It offers a Magic tool which can convert a site into a table without any training sessions. It suggests users to download its desktop app if more complicated websites need to be crawled. Once you’ve built your API, they offer a number of simple integration options such as Google Sheets,, Excel as well as GET and POST requests. When you consider that all this comes with a free-for-life price tag and an awesome support team, is a clear first port of call for those on the hunt for structured data. They also offer a paid enterprise-level option for companies looking for more large scale or complex data extraction.
Mozenda
Mozenda is another user-friendly web data extractor. It has a point-and-click UI for users without any coding skills to use. Mozenda also takes the hassle out of automating and publishing extracted data. Tell Mozenda what data you want once, and then get it however frequently you need it. Plus, it allows advanced programming using REST API the user can connect directly with Mozenda account. It provides the Cloud-based service and rotation of IPs as well.
ScrapeBox
SEO experts, online marketers and even spammers should be very familiar with ScrapeBox with its very user-friendly UI. Users can easily harvest data from a website to grab emails, check page rank, verify working proxies and RSS submission. By using thousands of rotating proxies, you will be able to sneak on the competitor’s site keywords, do research on sites, harvesting data, and commenting without getting blocked or detected.
Google Web Scraper Plugin
If people just want to scrape data in a simple way, I suggest you choose the Google Web Scraper Plugin. It is a browser-based web scraper that works like Firefox’s Outwit Hub. You can download it as an extension and have it installed in your browser. You need to highlight the data fields you’d like to crawl, right-click and choose “Scrape similar…”. Anything that’s similar to what you highlighted will be rendered in a table ready for export, compatible with Google Docs. The latest version still had some bugs on spreadsheets. Even though it is easy to handle, notice to all users, it can’t scrape images and crawl data in a large amount.
Artículo en español: 3 Mejores Formas de Crawl Datos desde WebsiteTambién puede leer artículos de web scraping en el Website Oficial
Artikel auf Deutsch: Die 3 besten Methoden zum Crawlen von Daten aus einer WebsiteSie können unsere deutsche Website besuchen.
Author: The Octoparse Team
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Is Web Crawling Legal? Well, It Depends. | Octoparse

First of all, I am not a lawyer nor an expert. This article is only based on my experience working at Octoparse. If you’re facing real legality problems, please seek legal assistance accordingly.
Web crawling, also as known as data scraping or data scraping in technical terms, is a computer program technique used to scrape huge amounts of data from websites where regular-format data can be extracted and processed into easy-to-read structured formats. The uses for businesses or individuals or other purposes are countless.
Is web crawling legal? Well, it depends. There’s a lot of uncertainty regarding the legality of web crawling.
If you’re doing web crawling for your own purposes, then it is legal as it falls under fair use doctrine. The complications start if you want to use scraped data for others, especially commercial purposes. Quoted from, eBay v. Bidder’s Edge, 100 1058 (N. D. Cal. 2000), was a leading case applying the trespass to chattels doctrine to online activities. In 2000, eBay, an online auction company, successfully used the ‘trespass to chattels’ theory to obtain a preliminary injunction preventing Bidder’s Edge, an auction data aggregator, from using a ‘crawler’ to gather data from eBay’s website. The opinion was a leading case applying ‘trespass to chattels’ to online activities, although its analysis has been criticized in more recent jurisprudence.
As long as you are not crawling at a disruptive rate and the source is public you should be fine.
I suggest you check the websites you plan to crawl for any Terms of Service clauses related to scraping of their intellectual property. If it says “no scraping or crawling”, maybe you should respect that.
Here are my suggestions.
1. Scrape websites discreetly. Don’t scrape websites at a disruptive or violated rate without regard to the load you’re placing on the target servers.
2. Use the data discreetly. It’s better for everyone. You would have problems using the data scraped if the data is copyrighted. Use the data for legal purposes.
Author: The Octoparse Team
Top 20 Web Scraping Tools to Scrape the Websites Quickly
Top 30 Big Data Tools for Data Analysis
Web Scraping Templates Take Away
How to Build a Web Crawler – A Guide for Beginners
Video: Create Your First Scraper with Octoparse 7. X

How to crawl data from mobile app? | Develop Paper

By XiaoyuWeChat official account: Python Data ScienceZhihu: Python Data Analyst
Usually, most of our crawlers are for web pages, but with the increase of the number of mobile app applications, the corresponding crawling demand is also increasing, soData crawling of mobile appIt is a necessary skill for a reptile engineer. We know that I often use it when crawlingF12 developer toolsperhapsfiddlerTools like these to help us analyze browser behavior. How to use mobile app? Similarly, we can usefiddlerTo analyze. Well, this blog will show you how to use it on the computerfiddlerGrab the mobile app.
First of all, learn about Fiddler (Baidu Encyclopedia):
Fiddler is an HTTP protocol debugging agent tool, which can record and check all the HTTP communications between your computer and the Internet, set breakpoints, and view all the “in and out” Fiddler data (referring to cookies, HTML, JS, CSS and other files, which can let you modify the meaning randomly). Fiddler is simpler than other network debuggers because it not only exposes HTTP communication but also provides a user-friendly format.
The whole process of completing this work can be divided into the following steps.
1. Download Fiddler packet capturing tool
fiddlerOfficial download link for: There is nothing special about the installation steps. The next step is normal.
2. Set fiddler
Here are two points to explain.
Set allow grabsHTTPSInformation package
The operation is very simple. Open and download itfiddler, foundTools -> Options, and thenHTTPSUnder the toolbar ofDecrpt HTTPS traffic, check under the new pop-up options barIgnore server certificate errors。
Set allow external devices to sendHTTP/HTTPSreachfiddler
Same atConnectionsCheck under Options barAllow remote computers to connect, and remember the port number above8888, which will be used later.
OK, the required Fiddler settings are configured.
3. Set the mobile terminal
Before setting up the mobile terminal, we need to remember one thing:Computers and mobile phones need to operate in the same network。have access towifiperhapsMobile hotspotWait to finish.
If you have put your computer and mobile phone in the same network, we need to know the networkIP address, which can be entered at the command lineipconfigSimple acquisition, as shown in the figure.
OK, let’s start setting up the mobile terminal.
Mobile app grabbing operationAndroidandAppleAll the systems are available, and the apple system used by the blogger is taken as an example here.
Access to mobilewifiIn the setting interface, select more information about the current network connection. In apple, it is aexclamation mark。 And then at the bottom you’ll see proxy Click to enter.
After entering, fill in the aboveIP addressandPort number, OK to save.
4. Download Fiddler security certificate
Open the browser on the mobile phone and input aIP address and port numberComposed URL:: 8888, then clickFiddlerRoot certificatedownloadFiddler certificate。
All the above operations are simply completed. Finally, we test whether it is easy to use.
5. Mobile terminal test
WithZhihu appFor example, on a mobile phoneZhihu app。 Here is the computerfiddlerThe result of capturing the package.
No problem. Get the packet. Then we can use our method of analyzing web pages to carry out subsequent operations.
WeChat official accountPython Data Science, get120GArtificial intelligence learning materials.

Frequently Asked Questions about how to crawl data

Is crawling data legal?

If you’re doing web crawling for your own purposes, then it is legal as it falls under fair use doctrine. The complications start if you want to use scraped data for others, especially commercial purposes.Jan 26, 2021

How do you crawl data from an app?

How to crawl data from mobile app?Download Fiddler packet capturing tool. fiddler Official download link for: https://www.telerik.com/downl… … Set fiddler. Here are two points to explain. … Set the mobile terminal. … Download Fiddler security certificate. … Mobile terminal test.Jun 19, 2020