Note: The tool is no longer maintained and no new accounts will be created. Due to technical constraints, we cannot guarantee that existing accounts will be accessible in the future.

CAT, the Content Annotation Tool (formerly known as CELCT Annotation Tool), is a general-purpose web-based text annotation tool.
The aim of the tool is to make the annotation activity as intuitive as possible, supplying, at the same time, a rich set of features. The main strengths of CAT are flexibility, usability and customizability. It also supports multi-layer annotation in order to combine the annotation of several linguistic/semantic levels. It provides a standardized XML stand-off output format to help convertibility, and it contains useful features for searching in files and for measuring inter-annotator agreement between two or more annotators.
CAT is freely available for research purposes.


  • Bartalesi Lenzi, V, Moretti, G, Sprugnoli, R, 2012 “CAT: the CELCT Annotation Tool”. In Proceedings of LREC 2012, Istanbul. (.pdf)

Application cases

Since now the tool has been employed by more than 100 users in the following projects:

  • Italian-TimeBank: corpus of Italian news annotated with temporal and event information following the It-TimeML specifications;
  • TERENCE: semantic annotation of stories for children;
  • Excitement: textual entailment annotation;
  • NewsReader: semantic annotation of news in the financial domain;
  • EVENTI task at EVALITA 2014 evaluation campaign.