Fess vs Sync-in Server
Fess and Sync-in Server are both search engine software. Fess is open source under Apache-2.0, with 1.1k GitHub stars. Sync-in Server is open source under AGPL-3.0, with 2k GitHub stars.
Which to pick
- Pick Fess when
- Your organisation wants one internal search across intranet sites and file shares without building on Elasticsearch directly.
- Pick Sync-in Server when
- A small organisation wants a lighter Nextcloud alternative focused on files, sharing and document editing on its own servers.
Side by side
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.
A self-hosted file storage and sharing server with spaces, permissions, public links, full-text search, WebDAV and online editing through Collabora or OnlyOffice.
A Java and OpenSearch stack to run, and the community is small and centred in Japan.
The project is little more than a year old with a small team, so its long-term support is unproven next to Nextcloud or ownCloud.
Production-ready
Usable
Self-hosted server (both)
Java and OpenSearch
TypeScript, Node.js and Angular
Open source, Apache-2.0 (permissive)
Open source, AGPL-3.0 (network copyleft)
You can build it into a product you sell, as long as you keep its copyright notice.
Use inside your business is unrestricted. If you change it and let customers use it over the internet, you must publish your changes.
1.1k GitHub stars
2k GitHub stars
Established: started 13 years ago, latest release fess-15.9.0.
Young: started 15 months ago, latest release v2.6.2.
Other comparisons
More search engines for apps and sites
Both sides were judged on 2026-11-03 from each project's README and GitHub data. License, age and popularity lines are worked out directly.