Plugin: Markdown Formatter

Plugins
1

Note
This plugin was created entirely with AI tools.

Note
This plugin only works in the Markdown editor.

Markdown Formatter

A Joplin plugin that formats the current note's Markdown with some configurable rules.

The plugin parses Markdown to find known structures, then applies targeted edits to the original text. Syntax it does not explicitly understand is left alone.

example

Features

  • Normalize unordered list markers to - or *.
  • Renumber ordered lists sequentially while preserving the first item's number.
  • Normalize emphasis and bold delimiters.
  • Normalize heading levels so they increase by at most one level at a time.
  • Normalize list spacing: semantic (keep each list tight or loose as authored, fixing mixed spacing), preserve, tight, or loose.
  • Normalize nested list indentation with tabs, 2 spaces, or 4 spaces.
  • Normalize Horizontal rule format and spacing above/below.
  • Optionally align GitHub Flavored Markdown tables.
  • Ensure headings, code blocks, math blocks, tables, and blockquotes have a blank line before and after neighboring content.
  • Ensure YAML front matter has a blank line before following content.
  • Collapse repeated blank lines outside protected content.
  • Trim trailing whitespace outside protected content, preserving two-space hard line breaks.
  • Ensure the note ends with exactly one trailing newline.
  • Apply changes through CodeMirror so formatting is undoable with Joplin's normal undo command.

Usage

Install the plugin, open a Markdown note, then:

  • Edit -> Format Markdown
  • Ctrl+Alt+F on Windows/Linux
  • Cmd+Alt+F on macOS
  • Click Format Markdown button in the formatting toolbar

The command formats the currently open note. If the note is already formatted, it does not write the note
back.

Settings

Settings are available under Markdown Formatter in Joplin's plugin settings.

Setting Default Description
Unordered list marker - Rewrite unordered bullets to dash or asterisk.
Normalize ordered list numbering On Renumber ordered lists sequentially, keeping the first item number.
Normalize heading level increments On Lower skipped heading levels so headings increase one level at a time.
Emphasis (italic) marker *emphasis* Prefer * or _ for emphasis delimiters.
Bold marker **bold** Prefer ** or __ for strong delimiters.
List spacing Semantic Semantic keeps each list tight or loose as authored and only fixes mixed spacing, so rendering never changes. Preserve, tight, and loose are also available.
List indentation Tabs Indentation used before nested list markers.
Align table columns Off Pad table cells so pipes line up.
Ensure blank lines around headings On Add one blank line before and after headings with neighboring content.
Ensure blank lines around code blocks On Add one blank line before and after code blocks with neighboring content.
Ensure blank lines around math blocks On Add one blank line before and after math blocks with neighboring content.
Ensure blank lines around tables On Add one blank line before and after tables with neighboring content.
Ensure blank lines around blockquotes On Add one blank line before and after blockquotes with neighboring content. Quote interiors are never rewritten.
Ensure blank line after front matter On Add one blank line between YAML front matter and following content.
Collapse consecutive blank lines On Reduce runs of blank lines to one blank line outside protected content.
Trim trailing whitespace On Remove trailing spaces and tabs outside protected content, preserving two-space hard line breaks.
Ensure trailing newline On End the note with exactly one newline.
Display toast messages On Show a toast after formatting with the number of characters added and removed.

Safety Model

The formatter follows a "parse for analysis, edit the original text" model. Each rule runs as a separate
pass:

  1. Parse the current Markdown.
  2. Locate structures the rule understands.
  3. Apply small string edits to the original source.
  4. Parse again and verify that the document structure still matches.

If a rule's edits would change the parsed document structure in an unexpected way, that rule is skipped
and the note is left with the last safe output. If formatting fails, the plugin leaves the original note
unchanged.

Protected content such as fenced code blocks, indented code blocks, inline code, YAML front matter, math,
and HTML blocks is preserved by whitespace-oriented rules.

Known Limitations

  • Lists inside blockquotes are not reindented and their tight/loose spacing is not changed. Their list
    markers and ordered numbering can still be normalized.
  • Tables inside blockquotes are not aligned.
  • Lists inside footnote definitions are not reindented.
  • Table alignment counts UTF-16 code units, so CJK and emoji content may not line up visually in every
    editor font.
  • Emphasis conversion to _ skips cases where CommonMark would reinterpret intraword underscores or
    merge adjacent delimiter runs.
2

Long time user of Markdown Prettier. Look forward to checking this out, it fixes a few small niggles I had with Prettier changing markers, e.g., *italic* to _italic_, horizontal line markers, and such.

Some very useful additional settings too. Love the work around headings, trailing newline, etc.

Thanks for the work! :+1:

Edit: Delighted to see it's also available for Android app

3

New guinea pig for scanner testing