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Fess vs Vespa: catalog facts
Fess	Vespa
Free Free and open source under Apache-2.0; commercial support is available.	Freemium Free and open source to self-host; Vespa Cloud is a paid service with a free trial.
Windows, macOS, Linux, Web, Self-hosted	Web, Self-hosted
Crawler, indexer, admin console and search UI included Indexes Office, PDF and archive files from many sources	Text, vector and hybrid retrieval with ranking in one engine Runs machine-learned models at query time
Non-Docker installs need a separate OpenSearch setup Requires Java 21 and server resources	Aimed at engineering teams rather than individual users Larger setup and learning effort than simpler search servers
Downloadable app, Self-hosted	Self-hosted, Hosted service
Open source	Open source
License: Apache-2.0	License: Apache-2.0
Not stated if an account is needed	Not stated if an account is 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.