How to Install ray in Python
Ray provides a simple, universal API for building distributed applications.
pip install ray
What is ray?
Ray provides a simple, universal API for building distributed applications.
Ray is a unified framework for scaling AI and Python applications. Ray consists of a core distributed runtime and a set of AI libraries for simplifying ML compute:
- : Scalable Datasets for ML - : Distributed Training - : Scalable Hyperparameter Tuning - : Scalable Reinforcement Learning - : Scalable and Programmable Serving
- : Stateless functions executed in the cluster. - : Stateful worker processes created in the cluster. - : Immutable values accessible across the cluster.
Quick Start
Minimal example to get started with ray:
import ray
print(ray.__version__)Installation
pip (standard)
pip install rayVirtual environment (recommended)
python -m venv venv
source venv/bin/activate # Windows: venv\Scripts\activate
pip install raypip3
pip3 install rayconda
conda install -c conda-forge rayPoetry
poetry add rayDependencies
Installing ray will also install these packages:
Verify the Installation
After installing, confirm the package is available:
python -c "import ray; print(ray.__version__)"If this prints a version number, installation succeeded. If you see a ModuleNotFoundError, see the errors section below.
Installation Errors
Common errors when installing ray with pip.
ModuleNotFoundError: No module named 'ray'
Cause: The package is not installed in the current Python environment.
Fix: Run pip install ray. If using a virtual environment, ensure it is activated first.
ModuleNotFoundError: No module named 'ray' (installed but still failing)
Cause: pip installed the package into a different Python than the one running your script.
Fix: Use python -m pip install ray to install into the interpreter you are running.
ImportError: cannot import name 'X' from 'ray'
Cause: The function or class does not exist in the installed version.
Fix: Check the version with pip show ray and upgrade with pip install --upgrade ray.
pip: command not found
Cause: pip is not in PATH or Python was not added to PATH during installation.
Fix: Try python -m pip install ray. On macOS/Linux try pip3.
PermissionError: [Errno 13] Permission denied
Cause: No write access to the system Python package directory.
Fix: Use a virtual environment, or add --user: pip install --user ray
SSL: CERTIFICATE_VERIFY_FAILED
Cause: pip cannot verify PyPI's SSL certificate — common behind corporate proxies.
Fix: Try: pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org ray
Recent Releases
| Version | Released |
|---|---|
2.54.1 latest |
2026-03-25 |
2.54.0 |
2026-02-18 |
2.53.0 |
2025-12-20 |
2.51.2 |
2025-11-29 |
2.52.1 |
2025-11-28 |
Manage ray
Upgrade to latest version
pip install --upgrade rayInstall a specific version
pip install ray==2.54.1Uninstall
pip uninstall rayCheck what is installed
pip show ray