An extremely fast Python package and project manager, written in Rust. fyn is an independent Python package manager built on uv's foundation, with telemetry removed, new features added, and long-standing bugs fixed. See MANIFESTO.md for the full story. A single tool to replace pip, pip-tools, pipx, poetry, pyenv, twine, virtualenv, and more. 10-100x faster than pip. Provides comprehensive project management, with a universal lockfile. Built-in task runner — define and run project tasks in pyproject.toml. Activates virtual environments with fyn shell. Upgrades dependencies in one command with fyn upgrade. Runs scripts, with support for inline dependency metadata. Installs and manages Python versions. Runs and installs tools published as Python packages. Includes a pip-compatible interface for a performance boost with a familiar CLI. Supports Cargo-style workspaces for scalable projects. Disk-space efficient, with a global cache for dependency deduplication. No telemetry — your installs are your business. Supports macOS, Linux, and Windows. From PyPI: # With pip. pip install fyn # Or pipx. pipx install fyn Or build from source: cargo install --path crates/fyn See the command line reference documentation with fyn help. fyn manages project dependencies and environments, with support for lockfiles, workspaces, and more, similar to rye or poetry: $ fyn init example Initialized project `example` at `/home/user/example` $ cd example $ fyn add ruff Creating virtual environment at: .venv Resolved 2 packages in 170ms Installed 2 packages in 1ms + ruff==0.5.0 $ fyn run ruff check All checks passed! $ fyn lock Resolved 2 packages in 0.33ms $ fyn sync Resolved 2 packages in 0.70ms Checked 1 package in 0.02ms Define tasks in your pyproject.toml and run them with fyn run: [tool.fyn.tasks] test = "pytest -xvs" lint = "ruff check ." format = { cmd = "ruff format .", description = "Format code" } check = { chain = ["lint", "test"], description = "Lint then test" } $ fyn run test # run...
First seen: 2026-03-23 13:05
Last seen: 2026-03-23 13:05