Deploying Voilà

The deployment docs are split up in two parts. First there is the general section, which should always be followed. Then there is a cloud service provider specific section of which one provider should be chosen.

If you are not sure where to deploy your app, we suggest Binder or Heroku. You can test deploying and serving your app without having to enter any credit card details, and with very little prior experience of deployments.

Setup an example project

  1. Create a project directory of notebooks you wish to display. For this tutorial we will clone Voilà and treat the notebooks folder as our project root.

    git clone
    cd voila/notebooks/
  2. Add a requirements.txt file to the project directory. This file should contain all the Python dependencies your Voilà app needs to run. For this tutorial we will copy the contents of the environment.yml of Voilà. We omit xleaflet and xeus-cling because these require extra work that is beyond the scope of this guide.


Cloud Service Providers

Deployment on Binder

Binder is one of the most accessible ways to deploy Voilà applications. The service is available at and is increasingly being used for reproducible research, making it an excellent fit for deploying Voilà applications.

  1. Make sure the repository is publicly available (on GitHub, Gitlab or as a gist).

  2. Follow this guide to prepare the repository. For simple deployments, steps listed in Setup an example project will be sufficient.


Binder also supports environment.yml files and conda environments.

  1. Go to and enter the URL of the repository.

  2. In Path to a notebook file, select URL and use the Voilà endpoint: /voila/render/path/to/notebook.ipynb

  3. Click Launch.

  4. Binder will trigger a new build if this is the first launch (or if there has been new changes since the last build). This might take a few minutes to complete. If an image is already available, the server will be able to start within a few seconds.

Customizing Voilà on Binder

To specify different options (such as the theme and template), create a jupyter_config.json file at the root of the repository with the following content:

  "VoilaConfiguration": {
    "theme": "dark",
    "template": "gridstack"

An example can be found in the voila-demo repository.

Deployment on Heroku is an attractive option if you want to try out deployment for free. You have limited computing hours, however the app will also automatically shutdown if it is idle.

The general steps for deployment at Heroku can be found here. High level instructions, specific to voila can be found below:

  1. Follow the steps of the official documentation to install the heroku cli and login on your machine.

  2. Add a file named runtime.txt to the project directory with the following content:

  3. Add a file named Procfile to the project directory with the following content if you want to show all notebooks:

    web: voila —-port=$PORT --no-browser

    Or the following if you only want to show one notebook:

    web: voila —-port=$PORT —-no-browser your_notebook.ipynb
  4. Initialize your git repo and commit your code. At minimum you need to commit your notebooks, requirements.txt, runtime.txt, and the Procfile.

    git init
    git add <your-files>
    git commit -m "my message"
  5. Create an Heroku instance and push the code.

    heroku create
    git push heroku master
  6. Open your web app

    heroku open

To resolve issues, it is useful to see the logs of your application. You can do this by running:

heroku logs --tail

Deployment on Google App Engine

You can deploy on Google App Engine in a “flexible” environment. This means that the underlying machine will always run. This is more expensive than a “standard” environment, which is similar to Heroku’s free option. However, Google App Engine’s “standard” environment does not support websockets, which is a requirement for voila.

The general steps for deployment at Google App Engine can be found here. High level instructions specific to Voilà can be found below:

  1. Follow the “Before you begin steps” from the official documentation to create your account, project and App Engine app.

  2. Add an app.yaml file to the project directory with the following content:

    runtime: python
    env: flex
      python_version: 3
    entrypoint: voila --port=$PORT --no-browser
  3. Edit the last line if you want to show only one notebook

    entrypoint: voila --port=$PORT --no-browser your_notebook.ipynb
  4. Deploy your app

    gcloud app deploy
  5. Open your app

    gcloud app browse

Sharing Voilà applications with ngrok

ngrok is a useful tool to expose local servers to the public internet over secure tunnels. It can be used to share Voilà applications served by a local instance of Voilà.

The main use case for using Voilà with ngrok is to quickly share a notebook as an interactive application with


Don’t forget to exercise caution before exposing local apps and data to the public over the internet.

While Voilà does not permit arbitrary code execution, be aware that sensitive information could be exposed, depending on the content and the logic of the notebook.

It’s good practice to keep the ngrok tunnel connection short-lived, and limit its use to quick sharing purposes.

Setup ngrok

To setup ngrok, follow the Download and setup ngrok guide.

Sharing Voilà applications

  1. Start Voilà locally: voila --no-browser my_notebook.ipynb

  2. In a new terminal window, start ngrok: ngrok http 8866

  3. Copy the link from the ngrok terminal window. The links looks like the following:

  4. Send the link

  5. When using the ngrok link, the requests will be forwared to your local instance of Voilà.