brat rapid annotation tool (brat) - for all your textual annotation needs
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brat rapid annotation tool (brat)


brat (brat rapid annotation tool) is based on the stav visualiser which was originally made in order to visualise BioNLP'11 Shared Task data. brat aims to provide an intuitive and fast way to create text-bound and relational annotations. Recently, brat has been widely adopted in the community. It has been used to create well-over 50,000 annotations by the Genia group and several other international research groups for a number of annotation projects.

brat aims to overcome short-comings of previous annotation tools such as:

  • De-centralisation of configurations and data, causing synchronisation issues
  • Annotations and related text not being visually adjacent
  • Complexity of set-up for annotators
  • Etc.

brat does this by:

  • Data and configurations on a central web server (as Mark Twain said: "Put all your eggs in one basket, and then guard that basket!")
  • Present text as it would appear to a reader and maintain annotations close to the text
  • Zero set-up for annotators, leave configurations and server/data maintainence to other staff


In an attempt to keep all user-facing documentation in one place, please visit the brat homepage which contains extensive documentation and examples of how to use and configure brat. We apologise for only providing minimal documentation along with the installation package but the risk of having out-dated documentation delivered to our end-users is unacceptable.

If you find bugs in your brat installation or errors in the documentation, please file an issue at our issue tracker and we will strive to address it promptly.


brat itself is available under the permissive MIT License but incorporates software using a variety of open-source licenses, for details please see see


If you do make use of brat or components from brat for annotation purposes, please cite the following publication:

    author      = {Stenetorp, Pontus and Pyysalo, Sampo and Topi\'{c}, Goran
            and Ohta, Tomoko and Ananiadou, Sophia and Tsujii, Jun'ichi},
    title       = {{brat}: a Web-based Tool
            for {NLP}-Assisted Text Annotation},
    booktitle   = {Proceedings of the Demonstrations Session
            at {EACL} 2012},
    month       = {April},
    year        = {2012},
    address     = {Avignon, France},
    publisher   = {Association for Computational Linguistics},

If you make use of brat or its components solely for visualisation purposes, please cite the following publication:

  author    = {Stenetorp, Pontus and Topi\'{c}, Goran and Pyysalo, Sampo
      and Ohta, Tomoko and Kim, Jin-Dong and Tsujii, Jun'ichi},
  title     = {BioNLP Shared Task 2011: Supporting Resources},
  booktitle = {Proceedings of BioNLP Shared Task 2011 Workshop},
  month     = {June},
  year      = {2011},
  address   = {Portland, Oregon, USA},
  publisher = {Association for Computational Linguistics},
  pages     = {112--120},
  url       = {}

Lastly, if you have enough space we would be very happy if you also link to the brat homepage:

...the brat rapid annotation tool\footnote{


As with any software brat is under continuous development. If you have requests for features please file an issue describing your request. Also, if you want to see work towards a specific feature feel free to contribute by working towards it. The standard procedure is to fork the repository, add a feature, fix a bug, then file a pull request that your changes are to be merged into the main repository and included in the next release. If you seek guidance or pointers please notify the brat developers and we will be more than happy to help.

If you send a pull request you agree that the code will be distributed under the same license as brat (MIT). Additionally, all non-anonymous contributors are recognised in the file.


For help and feedback please contact the authors below, preferably with all on them on CC since their responsibilities and availability may vary:

  • Goran Topić <goran is s u-tokyo ac jp>
  • Sampo Pyysalo <smp is s u-tokyo ac jp>
  • Pontus Stenetorp <pontus is s u-tokyo ac jp>