Trrntzip.NET by GordonJ
A tool for batch conversion of archive types (7z to zip, for example)
qarmin/czkawka: Multi functional app to find duplicates, empty folders, similar images etc.
Airsequel/SQLiteDAV at selfh.st
SQLite as WebDav FS
instant.io
Sharefest
ShareFest - Web based p2p file sharing built on WebRTC Data Channels API