Jekyll on Github Pages: any way to add footnotes in Markdown?

I use kramdown for markdown parsing and it handles footnotes nicely.

Change this line in your _config.yml file:

markdown: redcarpet

to:

markdown: kramdown

As of Jekyll 3.0.0, kramdown is the default Markdown processor, so the example in OP's question now works out of the box. The pattern is:

Some text[^1].

Some other text[^2].

The identifier in the square brackets does not have to be numeric[^my_footnote].

[^1]: Some footnote.
[^2]: Other footnote.

[^my_footnote]: This also works fine.

Update 3rd Jan. 2020:

• GitHub has its own markdown processor GFM, which is an extension of CommonMark. Both kramdown and GFM can be used to render GitHub Flavored Markdown.
• Footnotes are not yet supported by GitHub Flavored Markdown, which means the above examples do not render correctly in the GitHub code repository.
• Kramdown is still the default Markdown renderer for Jekyll. With kramdown, the above examples render correctly on sites based on GitHub Pages.