WebAnno is a general purpose web-based annotation tool for a wide range of linguistic annotations. WebAnno offers annotation project management, freely configurable tagsets and the management of users in different roles. WebAnno uses technology from the brat rapid annotation tool for visualizing and editing annotations in a web browser. It supports annotation and visualization of arbitrarily large documents, pluggable import/export filters, the curation of annotations across various users, and farming out annotations to a crowdsourcing platform.
Currently, WebAnno allows POS, Named Entity, Dependency Parsing and co-reference resolution annotations. The architecture design allows to add additional modes of visualization and editing, when new kinds of annotations are to be supported.
The added value of WebAnno, as compared to previous annotation tools, is on the one hand constituted by its web-based interface to skilled as well as unskilled annotators, which unlocks a potentially very large workforce. On the other hand, the tool's support functionality for quality control and annotator management and curation lowers the entrance barrier for new annotation projects.
We created WebAnno to fulfill the following requirements:
- Flexibility: Support of several annotation layers, several import and export formats, and extendibility to other frontends.
- Web-based: Increased availability, distributed work, no installation effort.
- Open Source: Usability of our tool in future projects without restrictions, under the Apache 2.0 license.
- Quality and User Management: Integrated different user roles (administrator, annotator, and curator) support for several users, inter-annotator agreement measurement, data curation, and progress monitoring.
- Interface to Crowdsourcing: unlocking a very large distributed workforce.
- Pre-annotated and un-annotated documents: supporting new annotations, as well as manual corrections of automatic annotations.
The source code is provided under the Apache Software License (ASL) version 2.