uv is Astral’s Rust-built Python package and project manager that replaces pip, pip-tools, pipx, poetry, pyenv, and virtualenv in one tool. It is 10-100x faster than pip. If you see ModuleNotFoundError: No module named ‘uv’, you actually want to install uv as a standalone CLI tool, not as a Python module.
Important: uv is mostly used as a CLI command (uv pip install ..., uv run script.py), not as import uv in Python code. Install via curl or pipx, not regular pip install.
Step 1: Install uv (recommended methods)
# Linux / macOS (recommended, isolated install):
curl -LsSf https://astral.sh/uv/install.sh | sh
# Windows PowerShell:
powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"
# Or via pipx (cross-platform):
pipx install uv
# Or via pip (if you really want it as a Python module):
pip install uv
Step 2: Verify install
uv --version
# uv 0.5.x
uv python list # show available Python versions
uv python install 3.12 # install a specific Python
Step 3: Common uv workflows
# Create a new project (pyproject.toml + .venv):
uv init my-app
cd my-app
uv add requests pandas
uv run python main.py
# Add packages to existing project:
uv add fastapi 'uvicorn[standard]'
# Install from requirements.txt (replaces pip):
uv pip install -r requirements.txt
# Sync exact versions (replaces pip-tools):
uv lock
uv sync
# Run a one-off script with deps inline (PEP 723):
uv run script.py
Why this error happens
| Cause | Fix |
|---|---|
| Tried “import uv” expecting a library | uv is a CLI tool, run as “uv …” in terminal |
| Installed but not on PATH | Restart shell, or add ~/.cargo/bin (Linux) / %USERPROFILE%\.local\bin (Win) |
| Confused with libuv (C async library) | Different project; Astral uv is what you want |
| Old install, wants pyvenv-uv | Update with: curl -LsSf https://astral.sh/uv/install.sh | sh |
Frequently Asked Questions
Why use uv instead of pip in 2026?
Speed: uv installs packages 10-100x faster than pip thanks to parallel downloads and a Rust-based resolver. It also bundles Python version management (replacing pyenv) and project management (replacing poetry). One tool, much less waiting.
Should I switch from poetry to uv?
For new projects in 2026, yes. uv has a near-identical pyproject.toml workflow, supports lockfiles, manages virtualenvs, and is dramatically faster. Existing poetry projects can usually be converted with: uv init –no-readme then uv add for each dep.
Does uv work with requirements.txt?
Yes. uv pip install -r requirements.txt is a drop-in replacement for pip install -r. You do not need to migrate to pyproject.toml just to use uv for speed.
Can uv install Python itself?
Yes. uv python install 3.12 downloads a portable Python build. uv automatically uses the right Python for each project based on pyproject.toml requires-python. Replaces pyenv for most users.
Is uv production-ready in 2026?
Yes. Reached 1.0-stable in late 2025. Used in major companies, including FastAPI, LangChain, and Polars CI pipelines. Backed by Astral (the team behind ruff). Open-source, MIT/Apache dual license.