---
id: npe2
version: "0.8.3"
license: BSD-3-Clause
license_treatment: permissive
maintenance: active
---

# npe2 — napari plugin engine v2

License: permissive · Maintenance: active · Downloads: 198.7K/mo

## What it is and what it does

npe2 is the plugin engine that powers napari's extensibility ecosystem. It provides tooling to define, validate, compile, and manage plugins that extend napari's core functionality for scientific imaging and domain-specific tasks. The package includes a command-line tool and programmatic API for plugin developers to build and distribute plugins, and for users to discover and manage installed plugins.

The engine handles plugin manifest validation, compilation of decorator-based plugin contributions into manifests, conversion of older napari plugins to the new format, and runtime plugin discovery. It depends on pydantic for schema validation, typer for CLI scaffolding, and rich for terminal output formatting.

Use it for:

- Build a napari plugin by using npe2 to compile @npe2.implements decorators into a valid plugin manifest
- Validate a plugin package before distribution to ensure its manifest conforms to npe2 specifications
- Convert an existing napari v1 plugin to the npe2 format using the convert command
- List and inspect all currently installed napari plugins and their manifests via CLI
- Fetch and parse plugin manifests from remote packages to understand plugin capabilities

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

npe2 is a plugin engine and management system for napari that enables discovery, validation, compilation, and installation of napari plugins through both CLI and programmatic interfaces.

Yes. npe2 is actively maintained, has no known vulnerabilities, and is either a direct dependency for napari plugin development or automatically installed with napari itself. Install it if you are building, validating, or managing napari plugins; it is not needed for end users simply running napari with plugins already installed.

## Install

pip install npe2
uv add npe2
poetry add npe2

## Installing npe2

Before you install: Low friction install with a pure-Python wheel. Actively maintained with a recent release (49 days ago) and current commit activity. Depends on well-established libraries like pydantic, typer, and rich.

License in practice: BSD-3-Clause permissive license allows commercial and private use with minimal restrictions; suitable for most projects.

Quickstart:

pip install npe2
npe2 --help
npe2 list
npe2 validate your-plugin-package

Requires Python 3.10 or later.

Verify before relying:

- Whether npe2 is required separately or automatically installed as a napari dependency in typical usage
- Performance characteristics when managing large numbers of plugins
- Backwards compatibility guarantees between npe2 versions for existing plugin manifests

## Package facts

- License: BSD-3-Clause (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 198.7K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

napari plugin management, plugin engine for napari, plugin manifest validation, napari plugin discovery, plugin compilation tool, plugin ecosystem management, plugin-system, scientific-imaging, napari-ecosystem

[View on SkillFed](https://skillfed.io/packages/npe2) · [View on PyPI](https://pypi.org/project/npe2/)