YaCy

YaCy is a self-hosted search engine stack combining a web crawler, an index, and a web UI for searching and managing content. It can run as a standalone search portal, an intranet search appliance, or as part of a decentralized peer-to-peer network that exchanges index data for web search.

Key Features

• Built-in web crawler with scheduling to keep indexes fresh
• Search UI plus administration interface for configuring crawls, indexes, and peers
• Peer-to-peer mode for sharing index data without relying on a central operator
• Standalone mode for private, local-only search results from your own index
• Intranet search use case with network scanning to discover HTTP, FTP, and SMB servers
• HTTP-based interfaces with XML/JSON outputs for many pages and functions

Use Cases

• Run a private search portal for a curated set of websites you crawl
• Provide intranet search across internal web services and shared resources
• Participate in a community-operated decentralized web search network

Limitations and Considerations

• Precompiled packages may be less frequent; building from source is commonly recommended
• Requires Java (11+) and can be resource-intensive depending on crawl and index size

YaCy is suited to organizations and individuals who want control over crawling and indexing, and who prefer privacy-aware search without dependence on a centralized search provider. Its flexible modes make it useful both for private indexing and for distributed web search participation.