API Reference: Annotorious

The standard version of Annotorious works with normal images embedded in websites or web applications. If you are looking for the Annotorious OpenSeadragon plugin, see here instead.


When included via <script> tag:

var config = {
  image: document.getElementById('my-image'),
  readOnly: true

var anno = Annotorious.init(config);

With npm:

import { Annotorious } from '@recogito/annotorious';
import '@recogito/annotorious/dist/annotorious.min.css';

const config = {
  image: document.getElementById('my-image')

const anno = new Annotorious(config);

The config object supports the following properties:

Property Type Default Description
allowEmpty Boolean false Annotations created without bodies are normally discarded. Set to true to allow empty annotations.
disableEditor Boolean false Disable the editor if you only need drawing functionality, but not the popup.
formatter Function - A formatter function providing custom style rules.
handleRadius Number 6 Radius of the shape resize handles.
image Elem | String - Required. Image DOM element or element ID.
locale String - Two-character ISO language code or auto to use the browser setting.
messages Object - Custom UI labels. Requires a message dictionary object.
readOnly Boolean false Display annotations in read-only mode.
widgets Array - A list of editor widget definitions (see this guide for details).

Instance Fields


console.log(anno.disableEditor); // true or fals
anno.disableEditor = !anno.disableEditor; // toggles state

Change the operation mode between normal (drawing tools & editor popup) and headless. In headless mode, only drawing tools and lifecycle events are active. The editor will not open.


console.log(anno.readOnly); // true or fals
anno.readOnly = !anno.readOnly; // toggles state

Change display mode between normal (annotations are editable) and read-only.

Instance Methods


anno.addAnnotation(annotation [, readOnly]);

Adds an annotation programmatically. The format is the W3C WebAnnotation model.

Argument Type Value
annotation Object the annotation according to the W3C WebAnnotation format
readOnly Boolean set the second arg to true to display the annotation in read-only mode



Register a drawing tool plugin.



Programmatically cancel the current selection, if any.



Delete all annotations from the image.



Clears the user auth information. Annotorious will no longer insert creator data when a new annotation is created or updated. (See setAuthInfo for more information about creator data.)



Destroys this instance of Annotorious, removing the annotation layer on the image.


const annotations = anno.getAnnotations();

Returns all annotations according to the current rendered state, in W3C Web Annotation format.


const selected = anno.getSelected();

Returns the currently selected annotation.


const { snippet, transform } = anno.getSelectedImageSnippet();

Returns an object containing:

Field Type Value
snippet Canvas the image under the current selection bounds as a CANVAS element
transform Function coordinate conversion function


const toolNames = anno.listDrawingTools();

Returns a list of the available drawing tools, including those from registered drawing tool plugins.



Loads annotations from a JSON URL. The method returns a promise, in case you want to perform an action after the annotations have loaded.

anno.loadAnnotations(url).then(function(annotations) {
  // Do something
Argument Type Value
url String the URL to HTTP GET the annotations from


anno.off(event [, callback]);

Unsubscribe from an event. If no callback is provided, all event handlers for this event will be unsubscribed.

Argument Type Value
event String the name of the event
callback Function the function used when binding to the event


anno.on(event, callback);

Subscribe to an event. (See Events for the list.)

Argument Type Value
event String the name of the event
callback Function the function to call when the event is emitted



Removes an annotation programmatically.

Argument Type Value
arg Object, String the annotation in W3C WebAnnotation format or the annotation ID



Saves the current selection. This is essentially a programmatic way to hit the Ok button on the editor.



Selects an annotation programmatically, highlighting its shape, and opening the editor popup.

Argument Type Value
arg Object, String the annotation or the annotation ID



Renders the list of annotations to the image, removing any previously existing annotations.

Argument Type Value
annotations Array array of annotations in W3C WebAnnotation format


var anno = Annotorious.init({ image: 'my-image' });

  id: 'http://recogito.example.com/rainer',
  displayName: 'rainer'

Specifies user authentication information. Annotorious will use this information when annotations are created or updated, and display it in the editor popup.

Editor popup example

Set this data right after initializing Annotorious, and in case the user login status in your host application changes. The argument to .setAuthInfo is an object with the following properties:

Property Type Value
id String REQUIRED the user ID, which should be a URI
displayName String REQUIRED the user name, for display in the UI

Annotorious will insert this data into every new annotation body that gets created:

  type: "Annotation",
  // ...  

    type: "TextualBody",
    value:"My comment",
    purpose: "commenting",
    created: "2020-05-18T09:39:47.582Z",
    creator: {
      id: "http://recogito.example.com/rainer",
      name: "rainer"



Switches between the different available drawing tools. Per default, Annotorious provides a standard rectangle tool (rect) and a standard polygon drawing tool (polygon).

More tools may be available through plugins. Use .listDrawingTool to get the list of registered tools.

Argument Type Value
toolName String E.g. rect or polygon



Shows or hides the annotation layer.

Argument Type Value
visible Boolean if true show the annotation layer, otherwise hide it


Set a “server time” timestamp. When using authInfo, this method helps to synchronize the created timestamp that Annotorious inserts into the annotation with your server environment, avoiding problems when the clock isn’t properly set in the user’s browser.

After setting server time, the Annotorious will adjust the created timestamps by the difference between server time the user’s local clock.


anno.updateSelected(annotation[, saveImmediately]);

Replace the currently selected annotation with the one given as argument to .updateSelected. Optionally: save the annotation immediately, triggering a createAnnotation or updateAnnotation event.

Important: this method returns a Promise. The update will not be effective immediately. Make sure you wait until the Promise completes before saving the annotation.

Use this method for applications that (with disableEditor set to true).

var anno = Annotorious.init({
  image: 'my-image'
  disableEditor: true

anno.on('createSelection', async function(selection) {
  selection.body = [{
    type: 'TextualBody',
    purpose: 'tagging',
    value: 'MyTag'

  // Make sure to wait before saving!
  await anno.updateSelected(selection);

  // Or: anno.updateSelected(selection, true);



anno.on('cancelSelected', function(selection) {

Fired when the user has canceled a selection, by hitting Cancel in the editor, or by clicking or tapping outside the selected annotation shape.

Argument Type Value
selection Object the canceled selection in W3C WebAnnotation format


anno.on('changeSelectionTarget', function(target) {

Fired when the shape of a newly created selection, or of a selected annotation is moved or resized.

Argument Type Value
target Object the W3C WebAnnotation target


anno.on('createAnnotation', function(annotation) {

Fired when a new annotation is created from a user selection.

Argument Type Value
annotation Object the annotation in W3C WebAnnotation format


anno.on('createSelection', function(selection) {

Fired when a new selection shape is drawn on the image.

Argument Type Value
selection Object the selection object in W3C WebAnnotation format


anno.on('deleteAnnotation', function(annotation) {

Fired when an existing annotation was deleted.

Argument Type Value
annotation Object the deleted annotation


anno.on('mouseEnterAnnotation', function(annotation, event) {

Fired when the mouse moves into an existing annotation.

Argument Type Value
annotation Object the annotation
event Object the original mouse event


anno.on('mouseLeaveAnnotation', function(annotation, event) {

Fired when the mouse moves out of an existing annotation.

Argument Type Value
annotation Object the annotation
event Object the original mouse event


anno.on('selectAnnotation', function(annotation) {

Fired when the user selects an annotation. Note that this event will not fire when the selection is made programmatically through the selectAnnotation(arg) API method.

Argument Type Value
annotation Object the annotation in W3C WebAnnotation format


anno.on('startSelection', function(point) {
  console.log(point.x, point.y)

Fired when the user starts drawing a new shape.

Argument Type Value
point Object the x/y coordinates of the start point (image pixel coordinates)


anno.on('updateAnnotation', function(annotation, previous) {

Fired when an existing annotation was updated.

Argument Type Value
annotation Object the updated annotation
previous Object the annotation state before the update


Per default, Annotorious renders annotations as SVG group elements with an a9s-annotation CSS class. A formatter function allows you to dynamically add additional attributes and elements to the SVG annotation shape.

A formatter is a JavaScript function takes a single argument - the annotation - and must return a string, a DOM element or an object.

String Example

 * This simple formatter will add an extra 'long' CSS class to 
 * long comments
var formatter = function(annotation) {

  var longComments = annotation.bodies.filter(function(body) {
    var isComment = body.type === 'TextualBody' && 
      (body.purpose === 'commenting' || body.purpose === 'replying');

    var isLong = body.value.length > 100;

    return isComment && isLong;

  if (longComments.length > 0) {
    // This annotation contains long comments - add CSS class
    return 'long';

var anno = Annotorious.init({
  image: document.getElementyById('my-image'),
  locale: 'auto',
  formatter: formatter

You can then apply a visual style to long comments in your own CSS stylesheet.

.a9s-annotation.long {

Object Example

 * This formatter will add usernames from the annotation as a data
 * attribute and apply an inline style (red outline) where multiple 
 * users have annotated
var formatter = function(annotation) {

  var contributors = [];

  annotation.bodies.forEach(function(body) {
    if (body.creator)

  if (contributors.length > 1) {
    return {
      'data-users': contributors.join(', '),
      'style': 'stroke-width:2; stroke: red'

var anno = Annotorious.init({
  image: document.getElementyById('my-image'),
  locale: 'auto',
  formatter: formatter