Markdown Footnotes: Syntax and Support

Basic footnote syntax

A footnote has two parts: an inline reference and a definition. Write the reference with a caret inside brackets, as in [^1]. Place the matching definition later in the document with the same label followed by a colon. The label must match exactly, including letters, numbers, and punctuation. A simple example is: The report uses a small sample.[^1] Then define it with: [^1]: Survey results from June. Most supporting text belongs in the definition, not inside the paragraph containing the reference. Keep the reference next to the claim it supports. This makes source review easier when you edit or reorder sections. Labels are identifiers, not displayed numbers. The renderer normally assigns the visible number based on document order. You can use descriptive labels such as [^method] and [^license] when that improves source maintenance.

Multiline notes and formatting

A definition can contain more than one line. Continue later lines with indentation when the target renderer supports multiline footnotes. For example, write [^details]: First line, then indent the next line by four spaces. You can include ordinary Markdown inside a footnote, such as emphasis, links, or a short list, but support varies by implementation. Keep notes compact because complex blocks can render differently across editors. A footnote definition does not need to appear immediately after its reference. Many authors place all definitions at the end of the document, which creates a predictable maintenance area. If your processor requires definitions to appear before use, follow its documentation instead. Do not reuse one label for unrelated evidence. One label can support multiple references when the same note applies to each location.

Compatibility and testing

Footnotes are an extension rather than a guaranteed feature of every Markdown parser. GitHub renders footnotes in supported Markdown files, while some CommonMark-focused tools require an extension or do not render them. A raw [^1] marker may remain visible if the parser lacks footnote support. Test the exact output destination, including a repository page, static-site generator, documentation portal, or email converter. Check the backlink from the note to the reference, keyboard navigation, and screen-reader labeling. If the destination does not support footnotes, replace them with linked endnotes or ordinary inline links. Keep the original source text available so you can convert it without losing citations. A generator can reduce label mistakes, but it cannot determine whether a target platform enables the feature.

Working example

This example cites a measurement and keeps the definition at the end of the document.

The test used 24 samples.[^sample]

[^sample]: Internal test log, June 2025.

The rendered paragraph shows a linked footnote number after “samples.” The note appears in a footnote area with a link back to the paragraph.

The exact number, backlink symbol, and placement depend on the Markdown renderer. Use the same target renderer for final verification.