Web crawling is the process of automatically retrieving (or “spidering”) web pages from the internet. A web crawler is a program that visits web pages, follows links on those pages, and visits the linked pages. The process of visiting all the pages on the internet is called crawling the web.
Web crawlers are used by search engines to index websites for their search engine results pages (SERPs). For example, when you use Google to search for “pizza”, the first few results that come up are websites that have been crawled and indexed by Google’s web crawlers.
Web crawlers can also be used for other purposes, such as website performance analysis or data mining.
Is web crawling legal?
Web crawling is the process of extracting data from websites. It is commonly used by search engines to build their searchable databases. While web crawling can be done manually, it is usually done automatically by software known as web crawlers. There are a few crawlers that are available for public use, but most operate behind the scenes.
U.S. law
Crawling the open web is generally legal in the United States. There are a few exceptions, but as long as you’re not scraping sensitive data or treading into trademark infringement, you’re in the clear.
To be sure, check your local laws and regulations. Some states have very strict data protection laws that could limit what you can crawl and how you can use the data. For example, California’s Online Privacy Protection Act (CalOPPA) requires businesses to get consent from users before collecting certain types of data, including browsing history and cookies. If you operate in California or collect data from California residents, you need to be compliant with this law.
At the federal level, there are a few laws that could come into play when crawling the web. The most relevant is probably the Computer Fraud and Abuse Act (CFAA), which prohibits unauthorized access to computers. However, courts have interpreted this law very broadly, and it’s not clear whether it applies to web crawlers. In one case, a court found that a company violated the CFAA by crawlings its website without permission, but this case is not binding precedent and other courts have reached different conclusions.
The other major federal law that could apply to web crawling is the Stored Communications Act (SCA), which prohibits accessing stored communications without authorization. This law has been interpreted to apply to email scraping, but it’s not clear whether it applies to other types of data scraping.
Overall, U.S. law is fairly permissive when it comes to web crawling. As long as you’re not scraping sensitive data or infringing on someone’s intellectual property rights, you’re unlikely to run into legal trouble.
E.U. law
In the European Union, the ruling is that personal data can only be collected for “specified, explicit and legitimate purposes” and any further processing of that data must be “compatible with those purposes.” This means that if you are collecting data through web crawling (or any other means), you must have a specific purpose in mind, and that any further use of that data must be compatible with that original purpose.
There are some exceptions to this rule. For example, if you are a news organization and you are crawling websites for stories, your purpose would be considered to be “legitimate” under the law. However, if you were to then take that data and sell it to a third party, such as a marketing company, that would not be considered a “compatible” use of the data and would therefore be illegal.
It is also important to note that even if you are collecting data for a legitimate purpose, you must still ensure that you are doing so in a way that does not violate the privacy rights of the individuals whose data you are collecting. For example, if you are crawling a website for contact information, you must make sure that you are only collecting information that is publicly available and that individuals have the opportunity to opt-out of having their information collected.
Other countries
Different countries have different laws regarding web crawling, so it’s important to research the laws in your country before you start crawling. In general, web crawling is legal as long as you respect the robots.txt file on the website you’re crawling and don’t overload the server with too many requests.
What can you do if you don’t want to be crawled?
Web crawling is the automated process of visiting web pages and extracting data. It is legal unless you don’t want to be crawled. There are a few ways to prevent web crawlers from crawling your website. You can disallow them in your robots.txt file or you can use a CAPTCHA.
Robots.txt
Robots.txt is a text file webmasters create to instruct web robots (typically search engine robots) how to crawl and index pages on their website.
The instructions in robots.txt are called “robots exclusion standard”. Creating a robots.txt file is entirely optional, but the directives in it can give you more control over how search engines crawl your website.
For instance, you might want certain pages of your site not to appear in search results, or you might want certain images not to be downloaded by web crawlers so they don’t eat up your bandwidth.
You can also use robots.txt as a security measure if you’re concerned about sensitive information appearing in search results (although this isn’t a foolproof method).
To learn more about the syntax of robots.txt files and how to create one, please see this article: How to Create a Robots.txt File
Meta tags
Meta tags are a type of code that can be added to the head of a web page to give instructions to web crawlers. One common use of meta tags is to tell web crawlers not to index a certain page, or not to follow any links on that page.
If you don’t want a web page to be crawled, you can add a “noindex” meta tag to the head of that page. This will tell most web crawlers not to index that page, which means it won’t appear in search results.
If you don’t want any links on a particular page to be followed, you can add a “nofollow” meta tag to the head of that page. This will tell most web crawlers not to follow any links on that page, which means they won’t be added to the search engine’s index.
You can also add both a “noindex” and “nofollow” meta tag to a page, which will tell most web crawlers not to index or follow any links on that page.
JavaScript
If you don’t want to be crawled, the best thing you can do is to use JavaScript to make it harder for crawlers to access your content. You can also use robots.txt to block crawlers from certain parts of your website, but this isn’t foolproof since some crawlers will ignore robots.txt rules.
Conclusion
No, web crawling is not illegal. However, there are some legal considerations that you should be aware of, such as data protection and copyright law. If you are using a web crawler for commercial purposes, it is advisable to seek legal advice to ensure that you are not breaking any laws.
