Comparison of web (text) annotation editors

Basic Features of Web Annotation Editors

A total of 60 web annotation tools are compared, highlighting their various features and functionalities. TinyMCE plugin 4A allows for document or fragment annotation in plain text, utilizing a dynamic tree structure with simple and structured content. It supports XML annotation format and is available under the Apache License 2.0. RDFaCE, another TinyMCE plugin, focuses on fragments with data in RDF, offering a linear list structure and offline capabilities, and is licensed under LGPL.

Pundit operates as a bookmarklet for fragment annotation, linking to ontologies and tags, but lacks a clear annotation format. It uses a structured approach with triples and is available under a dual licensing model: AGPL for client use and commercial for server use. Domeo, also a bookmarklet, provides similar functionalities with a focus on plain text and ontology searching, using HTTP for communication and Open Annotation format.

MAT, a web application, does not specify the content of annotations but allows for a linear list structure and uses JSON for annotation format. GATE Developer, a desktop application, offers a linear list of annotations but only supports text in name-value pairs and utilizes XML for its annotation format, licensed under LGPLv3.

WebAnno, another web application, allows fragment annotation with a selection from a predefined list, linking annotations through HTTP and exporting in binary format. The brat web application supports plain text fragment annotations with a selection of entity types and links between annotations, using the brat stand-off format.

Tools like Annotator and Annota provide JavaScript and Firefox add-on functionalities, respectively, for fragment annotation in plain text, with Annotator allowing for some formatting through plugins. A.nnotate enables document copy or fragment annotation with links between annotations, while TextAE provides named links between tagged entities.

BioQRator and Annotation Studio focus on fragments with linear list structures, the former utilizing BioC or CSV formats, and the latter supporting plain text and images. Hypothes.is, a bookmarklet, allows for formatted text annotation with autocomplete tags, while Annozilla offers a Firefox add-on for formatted text with predefined tags.

Other tools include Amaya, a desktop HTML editor that supports HTML annotations, and AnnotateIt, which allows for plain text annotations through a JavaScript application. Tools like Evernote and Diigo are commercial solutions providing various annotation capabilities, including drawing and tagging.

Advanced Features of Annotation Tools

In terms of advanced features, 4A stands out with its dynamic attribute structures and the ability to modify attributes with literals. It supports nested annotations and allows collaboration on annotations in real-time. RDFaCE, while limited in some areas, still provides nested annotations and a selection of text inside fragments.

Pundit offers a simpler model with triples but lacks the flexibility of dynamic attributes. Domeo allows for modular attributes and suggestions, while MAT also supports dynamic attributes but is less flexible in nesting capabilities. GATE Developer provides a dynamic structure but is limited to text annotations only.

Other Tools

Several additional annotation tools are noted that are either incomparable or not yet compared. These include SMORE, The SHOE Knowledge Annotator, WordFreak, MMAX2, and others such as Commentpress and iAnnotate. Some tools, like BioNotate and Hublog, have limited information available, while others like Sintelix are commercial offerings that require demos on demand.