Is Web Crawling Legal
Is web crawling legal? – Towards Data Science
Photo by Sebastian Pichler on UnsplashWeb crawling, also known as web scraping, data scraping or spider, is a computer program technique used to scrape a huge amount of data from websites where regular-format data can be extracted and processed into easy-to-read structured crawling basically is how the internet functions. For example, SEO needs to create sitemaps and gives their permissions to let Google crawl their sites in order to make higher ranks in the search results. Many consultant companies would hire companies to specialize in web scraping to enrich their database so as to provide professional service to their is really hard to determine the legality of web scraping in the era of the digitized crawling can be used in the malicious purpose for example:Scraping private or classified information. Disregard of the website’s terms and service, scrape without owners’ abusive manner of data requests would lead web server crashes under additionally heavy is important to note that a responsible data service provider would refuse your request if:The data is private which would need a username and passcodesThe TOS (Terms of Service) explicitly prohibits the action of web scrapingThe data is copyrightedViolation of the Computer Fraud and Abuse Act (CFAA). Violation of the Digital Millennium Copyright Act (DMCA)Trespass to “just scraped a website” may cause unexpected consequences if you used it probably heard of the HiQ vs Linkedin case in 2017. HiQ is a data science company that provides scraped data to corporate HR departments. Linkedin then sent desist letter to stop HiQ scraping behavior. HiQ then filed a lawsuit to stop Linkedin from blocking their access. As a result, the court ruled in favor of HiQ. It is because that HiQ scrapes data from the public profiles on Linkedin without logging in. That said, it is perfectly legal to scrape the data which is publicly shared on the ’s take another example to illustrate in what case web scraping can be harmful. The law case eBay v. Bidder’s Edge. If you’re doing web crawling for your own purposes, 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, 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 aggregation, 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 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 their intellectual property. If it says “no scraping or crawling”, you should respect ggestion:Scrape discreetly, check “” before you start scrapingGo conservative. Aggressively asking for data can burden the internet server. An ethical way is to be gentle. No one wants to crash the the data wisely. Don’t duplicate the data. You can generate insight from collected data, and help Your business out to the owner of the website before you start ’t randomly pass scraped data to anyone. If it is valuable data, keep it secure.
Is Web Scraping Legal ? – WebHarvy
Web Scraping is the technique of automatically extracting data from websites using software/script. Our software, WebHarvy, can be used to easily extract data from any website without any coding/scripting knowledge.
Is it legal to scrape data from websites using software? The answer to this question is not a simple yes or no.
The real question here should be regarding how you plan to use the data which you have extracted from a website (either manually or via using software). Because the data displayed by most website is for public consumption. It is totally legal to copy this information to a file in your computer. But it is regarding how you plan to use this data that you should be careful about. If the data is downloaded for your personal use and analysis, then it is absolutely ethical. But in case you are planning to use it as your own, in your website, in a way which is completely against the interest of the original owner of the data, without attributing the original owner, then it is unethical, illegal.
Also, while extracting data from websites using software, since web scrapers can read and extract data from web pages more quickly than humans, care should be taken that the web scraping process does not affect the performance/bandwidth of the web server in any way. Most web servers will automatically block your IP, preventing further access to its pages, in case this happens.
How to anonymously scrape data from websites?
Update: US federal court rules that web scraping does not violate hacking laws
Scrape Data Anonymously
WebHarvy is an easy-to-use visual web scraper which lets you scrape data anonymously from websites, thereby protecting your privacy. Proxy servers or VPNs can be easily used along with WebHarvy so that you are not connected directly to the web server during data extraction. Also, to minimize the load on web servers, and to avoid detection, there are options to automatically insert pauses & emulate a human user during the web scraping process.
Search engine scraping – Wikipedia
Search engine scraping is the process of harvesting URLs, descriptions, or other information from search engines such as Google, Bing, Yahoo, Petal or Sogou. This is a specific form of screen scraping or web scraping dedicated to search engines only.
Most commonly larger search engine optimization (SEO) providers depend on regularly scraping keywords from search engines, especially Google, Petal, Sogou to monitor the competitive position of their customers’ websites for relevant keywords or their indexing status.
Search engines like Google have implemented various forms of human detection to block any sort of automated access to their service,  in the intent of driving the users of scrapers towards buying their official APIs instead.
The process of entering a website and extracting data in an automated fashion is also often called “crawling”. Search engines like Google, Bing, Yahoo, Petal or Sogou get almost all their data from automated crawling bots.
Google is the by far largest search engine with most users in numbers as well as most revenue in creative advertisements, which makes Google the most important search engine to scrape for SEO related companies. 
Although Google does not take legal action against scraping, it uses a range of defensive methods that makes scraping their results a challenging task, even when the scraping tool is realistically spoofing a normal web browser:
Google is using a complex system of request rate limitation which can vary for each language, country, User-Agent as well as depending on the keywords or search parameters. The rate limitation can make it unpredictable when accessing a search engine automated as the behaviour patterns are not known to the outside developer or user.
Network and IP limitations are as well part of the scraping defense systems. Search engines can not easily be tricked by changing to another IP, while using proxies is a very important part in successful scraping. The diversity and abusive history of an IP is important as well.
Offending IPs and offending IP networks can easily be stored in a blacklist database to detect offenders much faster. The fact that most ISPs give dynamic IP addresses to customers requires that such automated bans be only temporary, to not block innocent users.
Behaviour based detection is the most difficult defense system. Search engines serve their pages to millions of users every day, this provides a large amount of behaviour information. A scraping script or bot is not behaving like a real user, aside from having non-typical access times, delays and session times the keywords being harvested might be related to each other or include unusual parameters. Google for example has a very sophisticated behaviour analyzation system, possibly using deep learning software to detect unusual patterns of access. It can detect unusual activity much faster than other search engines. 
HTML markup changes, depending on the methods used to harvest the content of a website even a small change in HTML data can render a scraping tool broken until it is updated.
General changes in detection systems. In the past years search engines have tightened their detection systems nearly month by month making it more and more difficult to reliable scrape as the developers need to experiment and adapt their code regularly. 
When search engine defense thinks an access might be automated the search engine can react differently.
The first layer of defense is a captcha page where the user is prompted to verify they are a real person and not a bot or tool. Solving the captcha will create a cookie that permits access to the search engine again for a while. After about one day the captcha page is removed again.
The second layer of defense is a similar error page but without captcha, in such a case the user is completely blocked from using the search engine until the temporary block is lifted or the user changes their IP.
The third layer of defense is a long-term block of the entire network segment. Google has blocked large network blocks for months. This sort of block is likely triggered by an administrator and only happens if a scraping tool is sending a very high number of requests.
All these forms of detection may also happen to a normal user, especially users sharing the same IP address or network class (IPV4 ranges as well as IPv6 ranges).
Methods of scraping Google, Bing, Yahoo, Petal or Sogou
To scrape a search engine successfully the two major factors are time and amount.
The more keywords a user needs to scrape and the smaller the time for the job the more difficult scraping will be and the more developed a scraping script or tool needs to be.
Scraping scripts need to overcome a few technical challenges:
IP rotation using Proxies (proxies should be unshared and not listed in blacklists)
Proper time management, time between keyword changes, pagination as well as correctly placed delays Effective longterm scraping rates can vary from only 3–5 requests (keywords or pages) per hour up to 100 and more per hour for each IP address / Proxy in use. The quality of IPs, methods of scraping, keywords requested and language/country requested can greatly affect the possible maximum rate.
Correct handling of URL parameters, cookies as well as HTTP headers to emulate a user with a typical browser
HTML DOM parsing (extracting URLs, descriptions, ranking position, sitelinks and other relevant data from the HTML code)
Error handling, automated reaction on captcha or block pages and other unusual responses
Captcha definition explained as mentioned above by
An example of an open source scraping software which makes use of the above mentioned techniques is GoogleScraper.  This framework controls browsers over the DevTools Protocol and makes it hard for Google to detect that the browser is automated.
When developing a scraper for a search engine almost any programming language can be used. Although, depending on performance requirements, some languages will be favorable.
PHP is a commonly used language to write scraping scripts for websites or backend services, since it has powerful capabilities built-in (DOM parsers, libcURL); however, its memory usage is typically 10 times the factor of a similar C/C++ code. Ruby on Rails as well as Python are also frequently used to automated scraping jobs. For highest performance, C++ DOM parsers should be considered.
Additionally, bash scripting can be used together with cURL as a command line tool to scrape a search engine.
Tools and scripts
When developing a search engine scraper there are several existing tools and libraries available that can either be used, extended or just analyzed to learn from.
iMacros – A free browser automation toolkit that can be used for very small volume scraping from within a users browser 
cURL – a command line browser for automation and testing as well as a powerful open source HTTP interaction library available for a large range of programming languages. 
google-search – A Go package to scrape Google. 
SEO Tools Kit – Free Online Tools, Duckduckgo, Baidu, Petal, Sogou) by using proxies (socks4/5, proxy). The tool includes asynchronous networking support and is able to control real browsers to mitigate detection. 
se-scraper – Successor of SEO Tools Kit. Scrape search engines concurrently with different proxies. 
When scraping websites and services the legal part is often a big concern for companies, for web scraping it greatly depends on the country a scraping user/company is from as well as which data or website is being scraped. With many different court rulings all over the world. 
However, when it comes to scraping search engines the situation is different, search engines usually do not list intellectual property as they just repeat or summarize information they scraped from other websites.
The largest public known incident of a search engine being scraped happened in 2011 when Microsoft was caught scraping unknown keywords from Google for their own, rather new Bing service,  but even this incident did not result in a court case.
One possible reason might be that search engines like Google, Petal, Sogou are getting almost all their data by scraping millions of public reachable websites, also without reading and accepting those terms.
Comparison of HTML parsers
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Scrapy Open source python framework, not dedicated to search engine scraping but regularly used as base and with a large number of users.
Compunect scraping sourcecode – A range of well known open source PHP scraping scripts including a regularly maintained Google Search scraper for scraping advertisements and organic resultpages.
Justone free scraping scripts – Information about Google scraping as well as open source PHP scripts (last updated mid 2016)
rvices source code – Python and PHP open source classes for a 3rd party scraping API. (updated January 2017, free for private use)
PHP Simpledom A widespread open source PHP DOM parser to interpret HTML code into variables.
SerpApi Third party service based in the United States allowing you to scrape search engines legally.
Frequently Asked Questions about is web crawling legal
Is Web scraping images legal?
Web Scraping is the technique of automatically extracting data from websites using software/script. … Because the data displayed by most website is for public consumption. It is totally legal to copy this information to a file in your computer.
Is Web scraping Google legal?
Although Google does not take legal action against scraping, it uses a range of defensive methods that makes scraping their results a challenging task, even when the scraping tool is realistically spoofing a normal web browser: … Network and IP limitations are as well part of the scraping defense systems.
Do you need permission for web scraping?
Web scraping and crawling aren’t illegal by themselves. After all, you could scrape or crawl your own website, without a hitch. The problem arises when you scrape or crawl the website of somebody else, without obtaining their prior written permission, or in disregard of their Terms of Service (ToS).Apr 18, 2017