How can I subscribe to updates of a package on PyPI?

Question 1

Yes, an RSS feed is available from pypi.org, see: https://pypi.org/rss/project/virtualenv/releases.xml

Question 2

Yes, it's possible.

libraries.io

The open(*) libraries.io service provides an e-mail notification service and RSS release feeds for Python package releases.

An RSS feed URL follows these pattern:

https://libraries.io/pypi/{PACKAGENAME}/versions.atom

Example:

curl -L https://libraries.io/pypi/virtualenv/versions.atom

For the email subscription you need to login via github/gitlab/bitbucket OAuth, but it just requests the email address over OAuth. After login you can browse to

https://libraries.io/pypi/{PACKAGENAME}

and hit the subscribe button to add a package to your subscriptions.

*open as in the server software being open source and the aggregated data being available under a creative commons license.

As of 2018-08, the libraries.io notifications aren't really reliable. For example, the PyPI release history page of a project has a new release and libraries.io doesn't send a notification mail nor updates the RSS feed for 11 days (and counting).

Anitya

Anitya (a.k.a. release-monitoring.org) is another open project for release notification. It originates from the Fedora context and Fedora infrastructure uses it, but it's basically open for anyone to create some email release notifications. Besides PyPI it supports monitoring other release sources.

A small howto:

sign-up/sign-in to release-monitoring.org
check if the PyPI packages you are interested in are already available, otherwise register the missing ones ('add project')
sign-up/sign-in to Fedora Notfications, create a new filter in the email section and add the 'Anything regarding a particular "upstream project"' rule from the Anitya rules listing. There you can specify a comma separated list of project names.

This service is supposed to check for new releases twice a day.

PyPI vs. pyup.io

As of 2018, pypi.org directly doesn't provide similar functionality. It just provides a release feed for all releases. But it links to libraries.io from each package page (for statistics). Pypi also links to similar notification services in the GitHub ecosystem.

For example, pyup.io implements notifications by connecting to one or many of your GitHub repositories - requiring a bunch of broad OAuth GitHub write permissions. It then periodically scans the repository's requirements file and is able to create pull requests if newer dependency versions are available.

Question 3

PyPI Notifier watches your projects' requirements.txt files and emails you when a required package is updated.

http://www.pypi-notifier.org

You connect with your GitHub account and select your repos.

Question 4

If you are interested in this to keep your installation up to date, you can use pip (as suggested on Super User):

$ pip list --outdated
pyflakes (1.2.3) - Latest: 1.3.0 [wheel]

Question 5

The Warehouse project that powers the
The Python Package Index (PyPI) at PyPI.org had a pull request to add support for "package update feeds" at URLs of the form /rss/{package_name}/updates.xml. That has been closed and in favour of a more general issue for a different, yet-to-be-implemented API.

When/if that goes live, that API will become the most direct and official way to get the updates you're after.

Question 6

I searched for a solution and https://newreleases.io seems to be perfect and up to date. I could not get email notifications working with libraries.io.

Question 7

There's now a package called yolk that will check PyPi for updates on your installed packages.

pip install yolk
yolk -l  # List all of the installed packages yolk can check
yolk -U  # Check PyPi for updates on the installed packages

It doesn't seem to work for Python 3 yet, although there is a Python 3 fork yolk3k. You can schedule this to go once a day and notify you in case there's a new version...