Published on 2025-08-07T06:18:08Z

CCBot

CCBot is the official web crawler for Common Crawl, a non-profit organization that builds and maintains a massive, open-source repository of web data. Its purpose is to scan the public web and archive the content, making it freely available for researchers, businesses, and AI developers. This data is a crucial resource for a wide range of applications, most notably for training large language models (LLMs).

What is CCBot?

CCBot is the web crawler for Common Crawl, a non-profit organization that provides an open repository of web crawl data accessible to the public. The bot's function is to systematically browse the internet, collecting and archiving public web content to build the Common Crawl corpus. This massive dataset is widely used for research, data analysis, and, significantly, as a primary training source for large language models (LLMs). The bot identifies itself in server logs with the user-agent string CCBot/2.0 (https://commoncrawl.org/faq/). It is designed to be a respectful crawler, adhering to robots.txt protocols.

Why is CCBot crawling my site?

CCBot is visiting your website to archive its publicly accessible content for the Common Crawl dataset. Its mission is to create a comprehensive snapshot of the public web, so any publicly available site may be visited. The frequency of its crawls depends on factors such as your site's size, popularity, and content update schedule. The crawling is not triggered by specific user actions but is part of the bot's regular, large-scale scanning schedule. This is considered authorized crawling for public content, and Common Crawl is transparent about its operations.

What is the purpose of CCBot?

The core purpose of CCBot is to collect web data to build the Common Crawl corpus, a valuable, free resource for a wide range of users. The dataset is instrumental in training AI and machine learning models, particularly large language models that power many modern AI applications. It also supports academic research on internet trends and the development of new search technologies. For website owners, having your content included in the dataset contributes to this broader technological ecosystem, though it may also raise concerns about bandwidth use or how the content is used in publicly accessible datasets.

How do I block CCBot?

If you do not want your website's content to be included in the Common Crawl dataset, you can block CCBot using your robots.txt file. This is the standard and respected method for opting out of the crawl.

To block CCBot, add the following lines to your robots.txt file:

User-agent: CCBot
Disallow: /

How to verify the authenticity of the user-agent operated by Common Crawl?

Reverse IP lookup technique

To verify user-agent authenticity, you can use host linux command two times with the IP address of the requester.

```
> host IPAddressOfRequest
```
This command returns the reverse lookup hostname (e.g., 4.4.8.8.in-addr.arpa.).

> host ReverseDNSFromTheOutputOfFirstRequest

If the output matches the original IP address and the domain is associated with a trusted operator (e.g., Common Crawl), the user-agent can be considered legitimate.

IP list lookup technique

Some operators provide a public list of IP addresses used by their crawlers. This list can be cross-referenced to verify a user-agent's authenticity. However, both operators and website owners may find it challenging to maintain an up-to-date list, so use this method with caution and in conjunction with other verification techniques.