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PyPI License codecov Open In Colab

custom jupyter widgets made easy

  • 🛠️ create widgets without complicated cookiecutter templates
  • 📚 publish to PyPI like any other Python package
  • 🤖 prototype within .ipynb or .py files
  • 🚀 run in Jupyter, JupyterLab, Google Colab, VSCode, and more
  • develop with instant HMR, like modern web frameworks

Learn more in the announcement.


Warning: anywidget is new and under active development. It is not yet ready for production as APIs are subject to change.

anywidget is available on PyPI and may be installed with pip:

pip install "anywidget[dev]"

It is also available on conda-forge. If you have Anaconda or Miniconda installed on your computer, you can install anywidget with the following command:

conda install -c conda-forge anywidget


import anywidget
import traitlets

class CounterWidget(anywidget.AnyWidget):
    # Widget front-end JavaScript code
    _esm = """
    export function render(view) {
      let getCount = () => view.model.get("count");
      let button = document.createElement("button");
      button.innerHTML = `count is ${getCount()}`;
      button.addEventListener("click", () => {
        view.model.set("count", getCount() + 1);
      view.model.on("change:count", () => {
        button.innerHTML = `count is ${getCount()}`;
    # Stateful property that can be accessed by JavaScript & Python
    count = traitlets.Int(0).tag(sync=True)

Front-end code can also live in separate files (recommend):

import pathlib
import anywidget
import traitlets

class CounterWidget(anywidget.AnyWidget):
    _esm = pathlib.Path("index.js")
    _css = pathlib.Path("styles.css")

    count = traitlets.Int(0).tag(sync=True)

Read the documentation to learn more.


This is a monorepo, meaning the repo holds multiple packages. It requires the use of pnpm. You can install pnpm with:

npm i -g pnpm

Then, create a Python virtual environment with a complete development install:

pip install -e ".[dev,test]"

or alternatively use the hatch CLI:

hatch shell

If you are using the classic Jupyter Notebook you need to install the nbextension:

jupyter nbextension install --py --symlink --sys-prefix anywidget
jupyter nbextension enable --py --sys-prefix anywidget

Note for developers:

  • the -e pip option allows one to modify the Python code in-place. Restart the kernel in order to see the changes.
  • the --symlink argument on Linux or OS X allows one to modify the JavaScript code in-place. This feature is not available with Windows.

For developing with JupyterLab:

jupyter labextension develop --overwrite anywidget

Sending PRs

Code styling

There are a few guidelines we follow:

  • For JavaScript, internal variables are written with snake_case while external APIs are written with camelCase (if applicable).
  • For Python, ensure black --check . and ruff . pass. You can run black . and ruff --fix . to format and fix linting errors.

Generating changelogs

For changes to be reflected in package changelogs, run npx changeset and follow the prompts.

Note not every PR requires a changeset. Since changesets are focused on releases and changelogs, changes to the repository that don't effect these won't need a changeset (e.g., documentation, tests).


The Changesets GitHub action will create and update a PR that applies changesets and publishes new versions of anywidget to NPM and PyPI.