> This page is for version 5.0 (Latest) (default).
> For other versions, use one of these documentation indexes:
> - 5.0 (Latest) (default): https://docs.nvidia.com/holoscan/sdk-user-guide/5-0-latest/llms.txt
> - ltsb-2.0: https://docs.nvidia.com/holoscan/sdk-user-guide/ltsb-2-0/llms.txt
> - 4.6: https://docs.nvidia.com/holoscan/sdk-user-guide/4-6/llms.txt
> - 4.5: https://docs.nvidia.com/holoscan/sdk-user-guide/4-5/llms.txt
> - 4.4: https://docs.nvidia.com/holoscan/sdk-user-guide/4-4/llms.txt
> - 4.3: https://docs.nvidia.com/holoscan/sdk-user-guide/4-3/llms.txt
> - Archives: https://docs.nvidia.com/holoscan/sdk-user-guide/archives/llms.txt

> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.nvidia.com/holoscan/sdk-user-guide/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/holoscan/sdk-user-guide/_mcp/server.

The Holoscan Python API requires Linux and Python 3.12 or newer. Install a
packaged SDK for application use, or import the package directly from an SDK
build tree when developing the SDK itself.

> **You will learn**
>
> * Where to find the release-specific Python package
> * How to build and import the package from an SDK checkout
> * How to verify the installed API and typing marker

## Install a packaged SDK

Use the distribution name and CUDA variant published with the Holoscan 5.x
release. The complete platform, driver, package, and CUDA prerequisites are
maintained on
[SDK installation](/holoscan/sdk-user-guide/setup/sdk-installation#python-wheel).
Do not reuse a Holoscan 4.x wheel name for a 5.x environment. Use an isolated
virtual environment when the application controls its Python dependency set.

## Import from an SDK build tree

Python bindings are enabled by default. From a source checkout, select an
explicit build directory and expose its package directory:

```bash
./run build --build-python true --buildpath build-holoscan
PYTHONPATH="$PWD/build-holoscan/python/lib" python3 -c \
  'import holoscan as hs; print(hs.__version__)'
```

The `PYTHONPATH` adjustment is for build-tree development only. An installed
package or wheel supplies its own import path and runtime-library layout.

## Verify operator discovery and typing

```python
import holoscan as hs

print(hs.__version__)
print(f"registered operators: {len(hs.registry.operators())}")
print(hs.RealtimeClock)
```

The distribution includes `.pyi` stubs and a `py.typed` marker, so type
checkers and editors can use the public facade signatures and generated
operator and reusable-graph proxy definitions without a separate stub package.

> **Warning**
>
> A third-party operator provider becomes visible only after its Python module
> or extension is imported. If a registry lookup reports an unknown operator,
> import the package that ships that operator before composing the graph.

## Recap

* Use Python 3.12 or newer and follow the release's package instructions for
  the installed CUDA major version.
* SDK contributors can import directly from `<build>/python/lib`.
* Stubs and `py.typed` ship with the package; operator providers register their
  types when imported.