Fess

Judgement

What it is

Complete system

What it does

A self-hosted enterprise search server on OpenSearch that crawls websites, file shares, databases and cloud sources and provides a search UI, REST API and RAG answers.

Adopt it when

Your organisation wants one internal search across intranet sites and file shares without building on Elasticsearch directly.

Watch out

A Java and OpenSearch stack to run, and the community is small and centred in Japan.

Ready for

Production-ready

Runs as

Self-hosted server

Built with

Java and OpenSearch

How established

Established: started 13 years ago, latest release fess-15.9.0.

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-03 from the project's README and GitHub data. The license and age lines are worked out directly.

Compare Fess

Built from

Follow it down: Fess → JDK → LLVM project → runs on a microchip

How compilers were built, back to punched paper tape

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