home edit page issue tracker

This page pertains to UD version 2.

Universal Dependencies tools

This page collects links to and minimal instructions for tools related to Universal Dependencies.

If you would like to have your tool added to this page, please write the UD mailing list.


UD-maintained tools

The Universal Dependencies project maintains a number of core tools for working with UD data. These tools are available from https://github.com/universaldependencies/tools and briefly described below.

Annotation statistics

There are two scripts that compute statistics, one written in Python and one in Perl. Despite similar names they are not equivalent!

python conllu-stats.py -h
python conllu-stats.py --stats ../UD_English/en-ud-train.conllu

perl conllu-stats.pl --help

The Perl script can be run in two main modes. In the default mode, it generates a XML file with statistics, including all tags, features and relations. This file is generated by the release team for every released treebank and the file stats.xml is then part of the release. The script is typically invoked from the treebank folder:

cat *.conllu | perl conllu-stats.pl > stats.xml

In the other mode, the script generates much more detailed statistics, which are then automatically included at appropriate places of the language-specific documentation. In this case the script needs to know where are all the treebank repositories and where is the docs repository. It will process all treebanks of one language in one run because there is only one docs section per language. It will write the statistics to the docs repository, which must be switched to the pages-source branch and must be afterwards pushed back to Github. This is usually also done at release time for all languages.

perl conllu-stats.pl --detailed --data .. --docs ../docs --lang pt

Consistency checking

(Description TODO)

Data validation

Validation of UD released treebanks is done using the script validate.py from the tools repository. More details are given on the release checklist page.

Format conversion

See Issue 376 for references to software that helps with migration of treebanks from UD v1 to v2 guidelines.

Third-party tools

Annotation Tools

brat rapid annotation tool

brat is a browser-based tool for text annotation. The brat visualization component is used in the UD documentation system and the tool comes with a custom configuration allowing it to be used for UD annotation .


WebAnno is a general purpose web-based annotation tool for a wide range of linguistic annotations including various layers of morphological, syntactical, and semantic annotations. Additionaly, custom annotation layers can be defined, allowing WebAnno to be used also for non-linguistic annotation tasks. WebAnno targets annotation teams in which all annotators work independently from each other. The tool includes facilities for curating/merging the annotations from multiple annotators, calculating inter-annotator agreement, and project management. Additional features include a correction and automation mode as well as decent support for right-to-left languages.

Since version 3.0.0, WebAnno supports importing and exporting data in the CoNLL-U format. If the data contains sub-token annotations, then the text is obtained from the subtokens and the surface text is added as annotations. To control which column dependencies end up in, the flavor feature of the built-in dependency layer needs to be used. If the feature is set to enchanced, then it goes to the enhanced dependencies column, otherwise to the basic dependencies column. It is currently up to the annotator to ensure that the dependency trees are well-formed and representable in CoNLL-U, otherwise export to CoNLL-U may fail.

WebAnno 3.0.0 does not support the CoNLL-U 2.0 format at this time.


DgAnnotator (Dependency Graph Annotator) is a visual tool for annotating text with syntactic information, in particular creating a dependency tree. The tool reads and produces annotated documents in both XML, CoNLL-X and CoNLL-U tab separated format. Additional features: shows the differences, highlighted in red, between two different dependency trees on the same corpus; generates PNG snapshots of trees; performs PoS tagging and parsing connecting to a network service; panning and zooming.

UD Annotatrix

UD Annotatrix is a browser-based offline + online annotation tool for dependency trees aimed at the UD community. It supports a number of features, including validation and two-level tokenisation.


Tred (Tree Editor) is a graph visualization and manipulation program written in Perl. It was the main tool used to annotate the Prague treebanks. It supports macros (in Perl) to automate frequently repeated operations. There are extensions for various annotation layers such as MWEs or coreference. Since January 2018, there is also an extension for CoNLL-U files (including multi-word tokens and enhanced dependencies).


Arborator is a manual dependency annotation tool supporting editing of POS tags and dependency relations in an easy to use drag and drop interface. It has project management features including specialized class-sourcing features, such as mixing in small amounts of gold data for evaluation/grading and assigning tasks to annotators. It supports color schemes for different labels and can read and write conll format dependencies. It now supports conllu input as well. There is also a ‘quick mode’ that can be used without setting up a project, just be copy-pasting conll data. For a demo, see here: https://arborator.ilpga.fr/q.cgi


LightTag is a general purpose text annotation tool which supports span annotations, classification as well as phrase-based and dependency-based relations. LightTag allows a drag-and-drop interface allowing annotators to easily drag individual tokens or sub-trees to construct their parse.

LightTag’s Universal Dependency Tool allows the user to paste an existing CoNLL-U file, visualize and correct the annotations. LightTag’s full featured text annotation tool supports managing teams of annotators, is fully hosted and availble free for academic use.


TrUDucer is a tree rewriting system based on tree transducers. It transforms dependency trees in a top-down fashion, making sure that each resulting structure will still be a valid tree. Rules are written in a domain-specific language; for cases where the DSL is not powerfui enough, rules can be augmented by writing special-case predicates in groovy. It contains an interactive transformation viewer to debug rule applications and a search tool to find trees where a specific rule could be applicable. As of 2018, TrUDucer is under active development at Hamburg University.

An example rule file converting (large parts of) the Hamburg Dependency Treebank to UD is provided with TrUDucer. The Univerity of Zurich provides a rule file to convert the TIGER treebank to UD using TrUDucer.


ConlluEditor is a tool which facilitates the editing of syntactic relations and morphological features of files in CoNLL-U format. It uses a Java-based server and a HTML/CSS/Javascript based front-end. The editor loads the CoNLL-U file and saves every change to disk (and performs a git commit if the file is under git version control).

The editor provides the following functionalities:

Editor modes


conllu-mode is an Emacs mode for editing CoNLL-U files (syntax highlighting, column alignment, shortcuts for navigation, etc).


This package provides syntax highlighting for CoNLL-U files in Atom.

Sublime Text

Syntax highlighting for CoNLL-U files on Sublime Text.

Processing tools


A Common Lisp library for various CoNLL-U-related operations. We have already functions for reading, writing, making queries, construct visualizations of sentences, compare trees etc.


DepEdit is a simple, open source, configurable tool for manipulating dependency trees, written in Python (2/3). It can be run standalone from the commandline or imported as a module, and it is available on PyPI (pip install depedit). Main features:

DKPro Core CoNLL-U reader/writer

DKPro Core is collection of software components for natural language processing (NLP) based on the Apache UIMA framework. DKPro Core can be used to build workflows that automatically process text using a wide range of NLP tools from third parties that are all interoperable (Stanford CoreNLP, Apache OpenNLP, ClearNLP, mate-tools, etc etc.). It also supports a range of different data formats and can be used to convert between the different supported formats.

Starting with version 1.9.0, DKPro Core supports reading and writing the CoNLL-U format.

The latest CoNLL-U 2.0 format is not yet supported.


pyconll is a minimal, entirely python, library for parsing and writing CoNLL-U files. pyconll allows users to easily parse out info from CoNLL-U corpora, or to perform and write corpus transformations. pyconll aims to provide a low-level interface over the CoNLL-U annotation scheme that is easy to understand and works with the current standard. Further, since it is written in python, there is no need to learn a new DSL or tool.


Treex is a modular natural language processing framework. It reads and writes data in many formats (including CoNLL-U) and provides API for dependency tree manipulation. Many treebanks have been harmonized in HamleDT and then converted to UD using Treex.


UDPipe is a trainable pipeline for tokenization, tagging, lemmatization and parsing of CoNLL-U files. UDPipe is language-agnostic and can be trained given only annotated data in CoNLL-U format. (Nevertheless, to train the tokenizer, either the SpaceAfter feature must be present, or at least some plain text must be available; also morphological analyzer and lemmatizer can be improved if morphological dictionary is provided.) Trained models are provided for nearly all UD treebanks. UDPipe is available as a binary, as a library for C++, Python, Perl, Java, C#, and as a web service.


Visualization tools


Deptreeviz is a SVG visualization and editing component. It can be used as a swing component or to create SVGs from the command line. It supports drag-and-drop modifications of trees, including dependency label and selecting the correct lexical items. For the editing facilities, a matching backend needs to be programmed. Deptreeviz is used to convert the Hamburg Dependency Treebank to UD.

CoNLL-U viewer

A simple browser-based (JavaScript, i.e. client side) viewer of your CoNLL-U files. Open your file, see the tree, go to the next tree. Click on a node to see all its attributes. Save the tree as an SVG graphics if needed. There is no way of jumping directly to a tree, neither by tree number, nor by searching attribute values.

CoNLL-U viewer at rug.nl


TüNDRA (Tübingen aNnotated Data Retrieval Application) is a web application for searching in treebanks using a lightweight query language inspired by the widely used TIGERSearch application. It offers corpus linguists an interface for using corpora with complex annotation and syntactic links. Most of the treebanks available in TüNDRA are free and publicly available. To access all the treebanks a user has to have an account at a European institution of higher education (i.e. be a student or an employee). Any user may upload a CoNLL-U or a TCF file to browse/search it with the tool. A visualization is interactive (scaling, zooming, panning) and can be saved in multiple formats (e.g. to be later used for a publication). TüNDRA is a part of CLARIN-D project and is funded by the German Federal Ministry for Education and Research (BMBF).