Fess: Enterprise Search Server
An open-source, self-hosted enterprise and site search server built on OpenSearch, with a web crawler for sites, file systems and databases, a REST API, and AI/RAG semantic search.
Fess is an enterprise search server that runs on any platform with a Java runtime, built on OpenSearch but configured entirely through a browser-based administration UI, with no prior OpenSearch knowledge required. A built-in crawler collects documents from websites, file systems, and data stores such as databases and CSV files, supporting many formats including Microsoft Office, PDF, and ZIP archives; it can also be embedded as a free, self-hosted alternative to Google Site Search.
It provides full-text search with faceting, sorting, and suggestions, a REST API, role- and permission-based filtering of results, single sign-on through LDAP, OpenID Connect, SAML, SPNEGO, or Microsoft Entra ID, a multilingual interface and text analysis in more than 20 languages, and extension points for data stores, ingest, scripts, and themes, alongside AI/RAG and semantic search features.
It requires Java 21 or later, and OpenSearch as its backend, bundled in the project's Docker images; it is released under the Apache-2.0 license.