Fyn is a privacy-first fork of uv, the popular Rust-based Python package manager, offering 10-100x faster performance than pip. Built as an independent tool, fyn removes telemetry while adding new features like built-in task runners and cache size limits. The project aims to replace multiple Python development tools with a single, unified solution.

Like its predecessor, fyn provides comprehensive project management with universal lockfiles, virtual environment activation, and Python version management. It supports Cargo-style workspaces for scalable projects and includes a pip-compatible interface for seamless migration. The tool runs on macOS, Linux, and Windows across x86_64 and aarch64 architectures.

Key differentiators include the fyn shell command for virtual environment activation, fyn upgrade for dependency management, and support for inline dependency metadata in scripts. Fyn also introduces explicit index support for transitive dependencies and environment variable support in index URLs. The project is dual-licensed under Apache 2.0 and MIT licenses, with contributions welcomed from developers of all experience levels.