RSyntaxTree is a graphical syntax tree generator for linguistic research.

Web App · Example Gallery · Documentation

Features

RSyntaxTree provides a rich set of features for creating publication-quality syntax trees:

Basic Syntax

Use bracket notation to define tree structures:

[S [NP the cat] [VP [V sleeps]]]

Text Decoration

Apply various text styles to node labels:

• Bold: **text**
• Italic: *text*
• Subscript: _text_
• Superscript: __text__
• Overline/Underline/Strikethrough: =text=, -text-, ~text~

Per-Node Coloring

Apply custom colors to individual nodes using @color: syntax:

[S [@red:NP the cat] [@blue:VP sleeps]]

Supports named colors (red, blue, green, etc.) and hex colors (@#FF5733:).

Enclosures and Triangles

• Brackets: [#NP text] → draws brackets around the node
• Rectangle: [##NP text] → draws a rectangle around the node
• Triangle: [^NP the quick fox] → draws a triangle connector

Combine with colors: [#@red:NP text], [^@blue:VP phrase]

Region Shade

Shade the whole subtree a node governs with a semi-transparent plane — useful for c-command/binding domains and cognitive grammar dominions. Prefix the node with %; the color reuses the @color: syntax (bare % is gray):

[TP [DP everyone] [%@lightblue:T' [T will] [VP praise it]]]

Path Drawing

Connect nodes with lines or arrows:

[S [NP+1 text] [VP [V+>1 connects]]]

Multiple Output Formats

Generate trees in PNG, SVG, PDF, JPG, GIF, or LSIF (JSON) format.

Web Interface

A working web interface is available at https://yohasebe.com/rsyntaxtree.

You can also run RSyntaxTree's web interface on your local machine using Docker Desktop. See RSyntaxTree Web UI.

Examples

See RSyntaxTree Example Gallery for examples covering:

• Generative Grammar
• Combinatory Categorial Grammar
• Head-Driven Phrase Structure Grammar
• Cognitive Grammar
• Construction Grammar
• Pragmatics
• Phonology
• and more

Input text

[S
  [NP |R|<>SyntaxTree]
  [VP
    [V generates]
    [NP
      [Adj #\+multilingual\
            \+beautiful]
      [NP syntax\
          trees]
    ]
  ]
]

Output (PNG or SVG)

System Fonts

RSyntaxTree resolves fonts by family name through fontconfig (measurement via Pango, rendering via librsvg), so the fonts must be installed on the system that generates the images. Recommended:

• Debian/Ubuntu: apt install fonts-noto-core fonts-noto-cjk fonts-noto-color-emoji
• Alpine: apk add font-noto font-noto-cjk font-noto-cjk-extra font-noto-emoji (the -extra package carries Noto Serif CJK)
• macOS: install Noto Sans/Serif (and Noto Sans/Serif JP for CJK); otherwise the system falls back to available fonts

Any script supported by an installed font renders correctly — the family chains fall back from Noto Sans/Serif to the JP and CJK variants, so Japanese, Chinese (simplified and traditional) and Korean are covered by the Noto CJK package. As of v1.8.0 the gem no longer bundles font files (they were not used at runtime).

Scripts outside Latin and CJK need their own Noto package, or they render as tofu boxes. Since v1.8.0 the gem names these families explicitly (Noto Sans Arabic, Noto Naskh Arabic, Noto Sans/Serif Hebrew, Devanagari, Thai, Khmer) instead of leaving them to the system fallback, so install them to get the intended shapes:

• Debian/Ubuntu: apt install fonts-noto-core already covers them; on minimal images add fonts-noto for the full set
• Alpine: apk add font-noto-arabic font-noto-naskh-arabic font-noto-hebrew font-noto-devanagari font-noto-thai font-noto-khmer

Emoji need the monochrome Noto Emoji; colour emoji fonts (NotoColorEmoji, shipped by Alpine's font-noto-emoji and Debian's fonts-noto-color-emoji) are measured but not drawn by the librsvg/Cairo pipeline, so emoji then fall back to whatever outline font happens to cover them.

Installation

gem install rsyntaxtree

macOS Installation Notice

Important for macOS users: If you encounter build errors for native extensions (gobject-introspection, cairo-gobject, gio2), run the following commands before installing RSyntaxTree:

gem install gobject-introspection -- --with-ldflags="-Wl,-undefined,dynamic_lookup"
gem install cairo-gobject -- --with-ldflags="-Wl,-undefined,dynamic_lookup"
gem install gio2 -- --with-ldflags="-Wl,-undefined,dynamic_lookup"

Then install RSyntaxTree:

gem install rsyntaxtree

Alternatively, use the Docker image or the web interface.

Usage

Command Line

Usage:
       1) rsyntaxtree [options] "[S [NP text] [VP here]]"
       2) rsyntaxtree [options] "(S (NP text) (VP here))"  # Penn Treebank format
       3) rsyntaxtree [options] "/path/to/text/file"
       4) echo "[S [NP text] [VP here]]" | rsyntaxtree [options]

Options

Option	Description	Default
-o, --outdir	Output directory	./
-f, --format	Output format: png, gif, jpg, pdf, svg, lsif	png
-l, --leafstyle	Leaf style: auto, triangle, bar, nothing	auto
-n, --fontstyle	Font style: sans, serif, cjk, mono	sans
-s, --fontsize	Font size: 8-26	16
-c, --color	Color mode: modern, traditional, off	modern
-p, --polyline	Polyline connectors: on, off	off
-d, --direction	Tree layout direction: ttb, ltr	ttb
--tidy	Layout scale: off, symmetric, low, medium, high	off
--hspacing	Horizontal spacing factor, all layout modes (0.5-3.0)	1.0
-m, --mirror	Flip the tree horizontally (RTL convention): on, off	off

Run rsyntaxtree -h for the full list of options.

Input Formats

• Bracket notation: [S [NP text] [VP here]]
• Penn Treebank format: (S (NP text) (VP here)) - automatically converted
• Standard input: echo "[S [NP text]]" | rsyntaxtree

Configuration File

RSyntaxTree supports configuration files (.rsyntaxtreerc) in YAML format. Place the file in your home directory or current working directory.

# ~/.rsyntaxtreerc
format: svg
color: modern
fontsize: 18

CLI options override config file settings.

Documentation

For detailed documentation on syntax and markup:

• Documentation in English
• 日本語ドキュメント
• Example Gallery

How to Cite

If you use RSyntaxTree in your research, please cite it. You can use the "Cite this repository" button on GitHub (powered by CITATION.cff), or the following BibTeX entry (adjust version to the one you used):

@software{hasebe_rsyntaxtree,
  author  = {Hasebe, Yoichiro},
  title   = {RSyntaxTree: A graphical syntax tree image generator},
  url     = {https://yohasebe.com/rsyntaxtree},
  doi     = {10.5281/zenodo.21916150},
  version = {1.8.0},
  year    = {2026}
}

Related Blog Posts

• RSyntaxTree tag on yohasebe.com

Author

Yoichiro Hasebe (yohasebe@gmail.com)

License

RSyntaxTree is distributed under the MIT License.