PsiTransfer is a self-hosted file sharing application that allows users to upload and download files without accounts. It uses the tus resumable upload protocol for reliable large file transfers, supports password protection, one-time downloads, and archive downloads (zip/tar.gz). The backend is built with Node.js and Express, with a Vue.js frontend. The architecture is a monolith with a clear separation of concerns: an Express server handles routing, a file store manages disk I/O with path traversal protection, an in-memory database tracks metadata with garbage collection, and a custom tus protocol implementation (tusboy) handles resumable uploads. The codebase demonstrates good security practices (argon2 password hashing, input validation, safe filename handling) and is actively maintained with CI/CD, Docker support, and comprehensive tests.