About CASES: Frequently Asked Questions

What is CASES?

CASES is a website for showcasing, sharing, and teaching the computational practices that archivists and researchers in the archives are increasingly applying to digital archival materials. The site consists in project descriptions, lesson plans, and CASE files.

What is NBViewer?

nbviewer is a web application that lets you enter the URL of a Jupyter Notebook file, renders that notebook as a static HTML web page, and gives you a stable link to that page which you can share with others. nbviewer also supports browsing collections of notebooks (e.g., in a GitHub repository) and rendering notebooks in other formats (e.g., slides, scripts).

nbviewer is an open source project under the larger Project Jupyter initiative along with other projects like Jupyter Notebook, JupyterLab, and JupyterHub.

What is nbviewer.jupyter.org?

Project Jupyter runs a free, public instance of nbviewer at https://nbviewer.jupyter.org. You can use it to render Jupyter Notebooks or browse notebook collection on GitHub. In either case, the notebooks must have public web URLs.

The homepage of nbviewer.jupyter.org includes some examples for you to try.

How does nbviewer render notebooks?

nbviewer is written in Python and JavaScript, uses nbconvert to render notebooks, and uses Tornado as its web server.

You can install nbconvert locally and run jupyter nbconvert to get the same functionality (and more). See the nbconvert documentation for details.

Can nbviewer run my Python, Julia, R, Scala, etc. notebooks?

nbviewer does not execute notebooks. It only renders the inputs and outputs saved in a notebook document as a web page.

mybinder.org is a separate web service that lets you open notebooks notebooks in an executable environment, making your code immediately reproducible by anyone, anywhere. nbviewer shows an Execute on Binder icon in its navbar which

Why does the Execute on Binder button not appear for a notebook?

nbviewer only supports launching notebooks stored on GitHub or as Gists on Binder. Binder does support other providers directly on the mybinder.org site.

Why does the Execute on Binder button lead to a Binder failure?

Binder tries to build a Docker image containing the notebooks and requirements declared in a git repository. The build will fail if the repository has a Dockerfile, requirements.txt, environment.yaml, etc. with issues. We suggest letting the repository owner know about the problem or submitting a pull request to help fix it.

Why does a notebook not run correctly after I click the Execute on Binder button?

Binder builds a Docker image containing the notebooks in a git repository. Those notebooks may have requirements to run correctly such as libraries and data files. Binder can install these prerequisites as part of its build process, if the git repository declares them in a supported manner.

If a notebook does not run properly in its Binder environment, we suggest letting the repository owner know about the problem or submitting a pull request to help fix it.

Does JavaScript embedded in notebooks work on nbviewer rendered pages?

Yes. This fact allows plots from plot.ly, Bokeh, and Altair to remain interactive, for example. It also means arbitrary JavaScript maybe execute when you visit the page, as it would on any page you visit on the Internet.

Can I load a private notebook on nbviewer?

nbviewer.jupyter.org can only render notebooks that it can access on the public Internet. If you are working on a notebook on your local machine, you need to publish that notebook somewhere with a public URL (e.g., in a GitHub repository, as a gist) in order for nbviewer.jupyter.org to render it.

Hosting your own nbviewer server opens additional avenues for rendering private notebooks. For example, an nbviewer server on your university network can render notebook files accessible via URLs on that network. Please see the README in the nbviewer repository on GitHub for instructions and options.

Why do I get a 404: Not Found error from nbviewer?

The URL you are visiting most likely points to a notebook that was moved or deleted. If you clicked a link on a site that lead to the 404 error page, we suggest you contact the site auownerthor to report the broken link. If a notebook author gave you the URL, we recommend asking them for an updated link.

If you notice one of the links on the nbviewer.jupyter.org, please report it as a bug in the nbviewer issue tracker.

Why do I get a 4xx error when I try to view a notebook?

nbviewer fetches notebooks from upstream providers (e.g., GitHub, GitHub gists, a public webserver) which host the the notebook files. You will see 4xx errors if the provider doesn't respond, the file nbviewer receives is invalid, the file is not publicly accessible, and so on.

If you believe nbviewer is incorrectly showing a 4xx error for an accessible, valid notebook URL, please file a bug in the nbviewer issue tracker.

Why do I get a 5xx or fastly error when I try to view a notebook?

A 5xx error or an error page from fastly may indicate that the public nbviewer.jupyter.org site is being redeployed or is down. If the problem persists for more than a few minutes, please open a bug in the nbviewer issue tracker on GitHub including the URL you are visiting and the error you receive.

Why is nbviewer showing an outdated version of my notebook?

nbviewer caches rendered notebooks to cut down on rendering time for popular notebooks. The cache duration on nbviewer.jupyter.org is approximately 10 minutes. To invalidate the cache and force nbviewer to re-render a notebook page, append ?flush_cache=true to your URL.

We originally selected notebooks that we found and liked. We are currently soliciting links to refresh the home page using a Google Form. You may also open an issue with your suggestion.

How can I remove a notebook from nbviewer?

nbviewer does not store any notebooks, it only renders notebooks stored elsewhere on the web given their URLs. If you've found a notebook that you think should be removed from the web, you'll need to locate where it is hosted (e.g., on GitHub) in order to update or remove it

Can I use nbviewer to convert my notebook to a format other than HTML?

No. However, you can install nbconvert locally and run jupyter nbconvert to convert notebook files to a variety of format. See the nbconvert documentation for details.

Where is nbviewer.jupyter.org hosted?

OVHcloud graciously hosts nbviewer.jupyter.org. Thanks to OVHcloud, we are able to provider a public nbviewer instance as a free service.

nbviewer was generously hosted by Rackspace until March, 2020.

Can I access nbviewer.jupyter.org over https?

Yes. Please do.

Can I run my own nbviewer server?

Yes, absolutely. Please see the README in the nbviewer repository on GitHub for instructions and options.

How can I report a bug with nbviewer or suggest a feature?

Please select the appropriate issue template in the nbviewer issue tracker on GitHub.

Are there useful tools that work with nbviewer?

Where can I ask additional questions?

Please post your questions about using nbviewer in the Jupyter Community Forum or in the Jupyter Google Group. If you would like to propose an enhancement to nbviewer or file a bug report, please open an issue in the jupyter/nbviewer project on GitHub.