Web annotation

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A web annotation is an online annotation associated with a web resource, typically a web page. With a Web annotation system, a user can add, modify or remove information from a Web resource without modifying the resource itself. The annotations can be thought of as a layer on top of the existing resource, and this annotation layer is usually visible to other users who share the same annotation system. In such cases, the web annotation tool is a type of social software tool. For Web-based text annotation systems, see Text annotation.

Web annotation can be used for the following purposes:

  • to rate a Web resource, such as by its usefulness, user-friendliness, suitability for viewing by minors.
  • to improve or adapt its contents by adding/removing material, something like a wiki.
  • as a collaborative tool, e.g. to discuss the contents of a certain resource.
  • as a medium of artistic or social criticism, by allowing Web users to reinterpret, enrich or protest against institution or ideas that appear on the Web.
  • to quantify transient relationships between information fragments.

Comparison of web annotation systems[edit]

Many of these systems require software to be installed to enable some or all of the features below. This fact is only noted in footnotes if the software that is required is additional software provided by a third party.


Annotation system Private notes Private group notes Public notes Notification Highlighting Formatted text Notes
A.nnotate Yes Yes No Yes[1] Yes No Can annotate PDF, ODF, .doc, .docx, images, as well as web pages (but only a limited number in the free version)
Annotary Yes Yes Yes Yes Yes No Includes social features, following, and a social feed of notes. Unlimited and free bookmarking, annotating, and collaboration. Private use allowed.
Axiom[2] Yes Yes No Yes Yes No Axiom provides a better workflow to manage digital documents. It is a cloud-based collaboration platform that allows users to organize and annotate (mark-up) documents, web-pages and even videos. These digital assets and annotations can be shared to facilitate real-time collaboration. It empowers users to arrange their documents intuitively and it uses bookshelves to organize the documents, as opposed to the traditional file-folder system. Users can annotate using the pen, highlighter or sticky notes. These annotations can be labelled such that the tags can be used to cross-reference across all types of documents (including videos), which allows the user to manage their knowledge effectively. Axiom is also a social platform, and permits sharing of annotations and documents with others, making it easier to collect feedback on documents, web-pages or videos.
Chatterati No No Yes No No Yes Currently available as a Google Chrome extension. Allows its users to have a discussion, and vote on each other's comments.
Delicious Yes No Yes No No No 1000 character limit per page per user
Diigo Yes Yes Yes Yes Yes No Public annotations are only allowed for established users. Group tag dictionary feature to encourage tagging consistently within a group.
Genius No Yes Yes Yes Yes No Genius has a Chrome Extension, an iPhone App, and a subdomain (genius.it/) which you can prepend to any domain to annotate. This is in addition to their website, genius.com, where users can annotate lyrics, literature, news, and other categories.
Hypothes.is Yes Yes Yes Yes Yes Yes In February 2015, different features are announced,[3] such as private group annotation, semantic tagging, moderation, etc.
Marky Yes No No No Yes Yes Marky is a Web-based multi-purpose document annotation application (Social Admin-annotators application). You only need a server with php technology and one database to annotate documents with a browser. The annotation component handles both plain text and HTML documents. Web technologies, such as HTML5, CSS3, Ajax and JQuery, to offer an intuitive What-You-See-Is-What-You-Get editor. Admins can enter documents to be annotated by annotators and get annotations for relevant terms.Marky also offers the possibility of obtaining substantial data about the annotations, as the annotation agreement between users, rounds, F-score and more. this is a tool that allows annotate multiple annotation classes, each with a different color. Developed in 2013. License GPL.
Org-mode (with extensions) Yes No No[4] No[5] No Yes Emacs-based; requires technical knowledge to set up; not as user-friendly as some other solutions; non-Latin characters allowed in notes but not in tags
Pundit Yes No Yes No Yes No Supports text and image fragment annotations and semantic annotations, e.g. to state precise relations among annotated items and web resources (e.g. DBpedia.org). It is distributed as Chrome extension or AngularJS application. Licence AGPL 3.0[6]
Stickis Yes Yes Yes Yes No[7] Yes Blogs subscribed via Stickis will appear as annotations when they link to the current page. Any web content, including YouTube videos, can be inserted into a note.
yellow pen No No No No Yes No Browser extension for Google Chrome. You can point out important information in long webpages by highlighting text with your mouse. And you can share this highlighted version of page (with special short link) in social media, e--mail, IM etc. or just bookmark it. (By Marker.to)

Discontinued web annotation systems[edit]

  • The earliest web annotation system was probably CritLink, developed in 1997-98 by Ka-Ping Yee of the University of California.[8] CritLink worked as an HTML "mediator", hence not requiring additional software or browser extensions but having limited support for modern JavaScript-driven websites.
  • Annotea - a W3C project that tried to establish a standard for web annotation.
  • ThirdVoice - a system launched in 1999 that shut down due to lack of success in April 2001.[9]
  • Fleck* - launched in 2005 with much publicity as a stick-it notes application for the web. A patent, funding and marketing didn't stop it from failing. Discontinued in 2010.[10]
  • Google Sidewiki was part of Google Toolbar, and allowed users to write comments alongside any web page. It was discontinued in December 2011.
  • Dispute Finder was built by Rob Ennals while working for Intel. It attempted to automatically identify disputed claims on websites, highlight them, and link to comments and pages which corrected the dispute.
  • SharedCopy was an AJAX based web annotation tool that allowed users to mark-up, highlight, draw, annotate, cache, sticky-note and finally share any website.
  • Wikalong was a Firefox plugin created in 2004 that provided a publicly editable mediawiki page in the margin of any webpage. (It was later accessible in other browsers via a bookmarklet.) Common uses were note-taking and discussion about the website. On Google, the Wikalong margin provided a variety of useful tips and shortcuts for searching. The project was discontinued in 2009 when the storage wiki went offline. It had been suffering from link spam abuse.[11][12]

See also[edit]


  1. ^ See A.nnotate notifications
  2. ^ http://www.axiomnetworks.ca/
  3. ^ Hypothes.is roadmap
  4. ^ Technically, public annotations are possible via the "publish to HTML" feature of org mode -- but no method for notifications or discovery of public annotations written by others is currently known.
  5. ^ But local annotations can be exposed to a firefox browser using Fireforg.
  6. ^ "License - Pundit". Pundit. Retrieved 2016-01-27. 
  7. ^ Instead of highlighting a web page, you drag selected content from the webpage into the note.
  8. ^ Yee, Ka-Ping (2002). "CritLink: Advanced Hyperlinks Enable Public Annotation on the Web". CiteSeerX: 
  9. ^ Third Voice Trails Off, Wired News, April 4, 2001
  10. ^ Farewell Fleck.com, "The Next Web", May 10, 2010
  11. ^ Wikalong Firefox Addon, Oct 1, 2006
  12. ^ Wikalong website

Further reading[edit]

External links[edit]