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

yacybot

YaCyBot is the web crawler for YaCy, an open-source, decentralized, peer-to-peer search engine. Unlike traditional crawlers, YaCyBot instances are run by individual users in the YaCy network, not a central company. Its purpose is to scan websites to build a shared, distributed search index that is free from commercial influence. For website owners, being indexed by YaCyBot offers visibility to a privacy-conscious, decentralized community.

What is yacybot?

YaCyBot is the web crawler for the open-source, peer-to-peer search engine YaCy. It is a decentralized crawler, meaning that instances of the bot are run by individual participants in the YaCy network from all over the world. The bot's purpose is to scan websites to gather information for YaCy's shared search index. It identifies itself in logs with a user-agent string like yacybot (...) http://yacy.net/bot.html, which includes details about the specific node that is crawling.

Why is yacybot crawling my site?

YaCyBot is crawling your site to collect and index its content for the YaCy distributed search engine. Because the network is decentralized, crawling patterns can vary significantly. The bot may visit more frequently if your site is relevant to the interests of the YaCy community. Its crawling is generally authorized as part of a legitimate search indexing activity, and the bot is designed to respect standard web protocols.

What is the purpose of yacybot?

The purpose of YaCyBot is to support the YaCy search engine, which offers a decentralized alternative to the major search engines. The data it collects is used to build a search index that is not controlled by a single corporation, and whose results are not influenced by commercial algorithms. For website owners, being indexed by YaCyBot provides visibility to users who prefer privacy-focused, decentralized search options. The distributed nature of the index can also mean that it includes content that mainstream search engines might not prioritize.

How do I block yacybot?

To prevent YaCyBot from accessing your website, you can add a specific disallow rule to your robots.txt file. This is the standard method for managing access for web crawlers.

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

User-agent: yacybot
Disallow: /

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

Reverse IP lookup technique

To verify user-agent authenticity, you can use host linux command two times with the IP address of the requester.
  1. > host IPAddressOfRequest
    This command returns the reverse lookup hostname (e.g., 4.4.8.8.in-addr.arpa.).
  2. > host ReverseDNSFromTheOutputOfFirstRequest
If the output matches the original IP address and the domain is associated with a trusted operator (e.g., YaCy), 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.