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Fess vs Elasticsearch: catalog facts
Fess	Elasticsearch
Free Free and open source under Apache-2.0; commercial support is available.	Freemium Free to download and self-host; Elastic sells a hosted cloud service with a free trial.
Windows, macOS, Linux, Web, Self-hosted	Windows, Self-hosted
Crawler, indexer, admin console and search UI included Indexes Office, PDF and archive files from many sources	Full-text, vector and hybrid search through one API Scales horizontally across a cluster
Non-Docker installs need a separate OpenSearch setup Requires Java 21 and server resources	Running and tuning a cluster takes operational effort Aimed at developers and operators rather than end users
Downloadable app, Self-hosted	Downloadable app, Self-hosted, Hosted service
Open source	Open source
License: Apache-2.0	License not stated
Not stated if an account is needed	No account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.