From the product page

When you configure YaCy as your personal search appliance, all the arguments for a topic-oriented, corporate or personal-use search engine apply that also other search engine producers describe. But YaCy can do more: it is not limited to a specific number of documents (see usage licenses of other products). Compare: YaCy is scalable and free!

Open Alternative to Web Search Portals

YaCy was designed to create a large-scale search engine. The standard release of YaCy joins a public network that is supposed to be an alternative to other search portals.

Intranet Websearch

YaCy can index intranet content, but this functionality can only be obtained in a network defined for this purpose. With the ability of YaCy to organize a very large number of documents it is possible to outperform competitors in the field of intranet indexing easily. Please contact us, we will support you in the creation of your own high-performance intranet search.

Search Engine Optimizing

YaCy provides some analysis tools that could be useful for SEO purpose. For example:

• Web Structure Visualization: YaCy does a analysis of the link structure between domains and shows this as a web structure picture. This can be used to analyse the positioning of domains.
• Domain Listings: Large domain lists are hard to obtain. Using an analysis of the YaCy URL lists (i.e. 'loaded' URLS) such lists can be created.
• Dead Link Analysis: Web crawl failure cases are are documented in logs and can be extracted from failure databases. This is a good resource for a dead link analysis.