COMMON CRAWL

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Artificial intelligence systems like ChatGPT are now woven into daily life. These systems require enormous amounts of text to train effectively. Much of that text comes from publicly available material on the internet. One major source of that public web data is an organization called Common Crawl.

Many worry -- Is it collecting our private emails, such as Gmail; Does it harvest social media posts, such as Facebook or Instagram; Is it pulling content from paid services or personal accounts; and, Is it using submissions to ChatGPT?

Common Crawl is a nonprofit organization that builds and maintains a massive open archive of the public web. Its mission is simple but profound: to make web-scale data available to everyone, not just to giant corporations with enormous budgets. Universities, independent researchers, journalists, and startups use this data to study language, track trends, analyze misinformation, and develop new AI systems.

Common Crawl operates much like a search engine crawler. They download the HTML, extract text, and record metadata at enormous scale, covering billions of pages in a single crawl. The scale is staggering.

Common Crawl stores petabytes of web data and distributes it freely through cloud infrastructure provided by Amazon Web Services. Researchers across the world can access it. It is not sold. It is not secret. It is an open dataset.

Important, Common Crawl gathers only public content, not private data. That is an important distinction. It does not log into private accounts. It does not access email systems. It does not scrape private social media. It does not read ChatGPT conversations. Content behind passwords, paywalls, or authentication barriers is not part of its archive. It does include my blogs.

In the public imagination, “AI training data” often sounds shadowy or invasive. In reality, Common Crawl operates much like a large-scale public library that photocopies what is already sitting openly on the internet.

If you publish something publicly on the web, it may be crawled—just as search engines index it. If it is private, behind a login, or stored in your personal account, it is not accessible to Common Crawl.

For blog authors, including myself, this distinction is important. Public writing is part of the shared digital commons. Private communication remains private.

Understanding that boundary allows us to discuss AI, web archives, and digital knowledge with greater confidence—and less fear.

This essay aims to clarify those questions in plain terms.

How Is Content Gathered?

Common Crawl gathers data using automated software programs known as web crawlers. They start with a list of publicly accessible web addresses (URLs) and download the HTML content of those pages. They also extract links from those pages and follow those links to additional public pages. It retrieves content that is already publicly accessible to anyone with a browser, such as Google and Microsoft Bing.

The crawler does not “hack,” log in, or bypass security. It respects a website’s robots.txt file. It does not collect content behind password-protected accounts, private databases, direct messages, email inboxes, or cloud storage files.

The scale is enormous. Common Crawl conducts large crawls monthly. Each crawl may include billions of web pages and many terabytes of compressed data. Over time, the archive has grown into petabytes (millions of gigabytes) of stored web content.

The data is stored and distributed via Amazon Web Services (AWS). AWS donates significant storage and bandwidth infrastructure to support the project. Common Crawl is a nonprofit organization funded by philanthropic donations, grants, corporate sponsorship, and in-kind infrastructure support.

It does not sell the data. The archive is freely available to the public. Researchers and organizations can access the datasets directly through AWS’s public data program. Instead of downloading the entire web (which would be impractical for most), users can query and filter the data selectively in the cloud.

Universities, independent researchers, startups, journalists, and AI developers all use Common Crawl. Because the dataset is open, it reduces the barrier to entry for innovation. A graduate student can analyze global language trends without owning a data center. A small AI startup can experiment without first building its own web crawler.

Common Crawl is a public archive of publicly accessible web pages. It is not a surveillance system, a private inbox scraper, a password-breaking tool, or a database of personal communications. It does not log in. It does not bypass paywalls.

Common Crawl Does Not Gather Personal Data.

Common Crawl does not access private email accounts such as Gmail. Email inboxes require authentication. They are not publicly accessible web pages. A crawler cannot log in to your account. Therefore, your private emails are not collected.

Common Crawl does not systematically gather content from Meta Platforms (Facebook). Usually, they require login, are dynamically generated, and are protected by anti-crawling systems.

Public business pages, visible without login, could theoretically be crawled, but large-scale scraping of Facebook’s private user content is blocked and not part of Common Crawl’s mission.

Conversations with ChatGPT—including those in a Plus account—are not public web pages. They are not indexed by search engines and are not crawlable.

However, my two blogs, 

https://evanscenterAI.blogspot.com and https://evanscenterLFC.blogspot.com

may be included. They are publicly accessible, do not have robots.txt, and does not require login.

Personal or Low-Quality Data Is Removed

The Internet has a lot of crap. It contains spam, duplications, auto-generated junk, malware, broken HTML, and boilerplate text. Common Crawl has special filters to block most of this stuff.