Issues with labels like "feature", "enhancement", "duplicate"… are ignored
For the issue median closing time issues older than 6 months are ignored
~~Issues from collaborators are ignored~~ (GitHub updated their API and it's not possible anymore)

Ideas:

Reactivity: issue average acknowledgement time (i.e. first comment after the issue was open)

Dropped ideas:

Release frequency: depends a lot on the project, hard to say a frequency is "good" or "bad" (#2)
Last commit date (from all branches): same as #2

Run

$ composer install
$ bower install
$ php -S 0.0.0.0:8000 -t web web/index.php

The first time a badge is generated takes a few seconds, then it is cached. Be patient.

GitHub has an API rate limit that is reached very easily. To circumvent that, you can generate an API token (https://github.com/settings/applications) and set it in parameters.php.

Commands

bin/console stats:show user/repository: shows the statistics for a repository (skips the cache)
bin/console cache:clear: clears all the caches
bin/console cache:warmup: warmup the caches

Requirements

PHP 7.0
Puli installed
GD extension