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guideDevelopment tools

In this guide you will learn about developer tools that will help you develop and debug CKEditor 5 plugins and features.

# CKEditor 5 inspector

The official CKEditor 5 inspector provides a set of rich debugging tools for editor internals like model, view, and commands.

It allows you to observe changes to the data structures and the selection live in the editor, which is particularly helpful when developing new rich-text editor features or getting to understand the existing ones.

Screenshot of the CKEditor 5 inspector attached to a WYSIWYG editor instance.

# Importing the inspector

You can import the inspector as an @ckeditor/ckeditor5-inspector package into your project:

npm install --save-dev @ckeditor/ckeditor5-inspector

and then either import it as a module:

import CKEditorInspector from '@ckeditor/ckeditor5-inspector';

or as a plain <script> tag in the HTML of your application:

<script src="../node_modules/@ckeditor/ckeditor5-inspector/build/inspector.js"></script>

# Inspector as a bookmarklet

If you do not wish to import the inspector, you can create a bookmarklet in your browser instead that will allow you to open it on any page without interference with its source code.

Important note: this method will not work if the page has Content Security Policy enabled.

To create such a bookmarklet, paste the following code as the URL of a new bookmark in the browser of your choice:

javascript:(function(){let script=document.createElement('script');script.src='';script.onload=()=>CKEditorInspector.attachToAll();document.head.appendChild(script);})()

Now you can load CKEditor 5 inspector by using the newly created bookmark.

# Enabling the inspector

Attach the inspector to the editor instance when created using the CKEditorInspector.attach() method:

    .create( /* ... */ )
    .then( editor => {
        CKEditorInspector.attach( editor );
    } )
    .catch( error => {
        console.error( error );
    } );

The inspector will show up at the bottom of the screen.

# Inspecting multiple editors

You can inspect multiple CKEditor 5 instances at a time by calling CKEditorInspector.attach() for each one of them. Then you can switch the inspector context to inspect different editor instances.

You can specify the name of the editor when attaching to make working with multiple instances easier:

// Inspecting two editor instances at the same time.
CKEditorInspector.attach( 'header-editor', editor );
CKEditorInspector.attach( 'body-editor', editor );

The editor switcher is in the upper–right corner of the inspector panel.

# Demo

Click the “Inspect editor” button below to attach the inspector to the editor:

CKEditor 5 inspector demo

Click the button below to enable the CKEditor 5 inspector for this editor instance.

Once you do this, you can:

  • Browse and inspect the model and view structures.
  • Observe the selection position.
  • Check the list of commands and their state.
  • More features coming soon!

# Compatibility

The inspector works with CKEditor 5 v12.0.0+.

# Contributing to the inspector

The source code of CKEditor 5 inspector and its issue tracker is available on GitHub in

# Mr. Git

Mr. Git is a multi-repo manager for git. In CKEditor 5, it can be used for easy development and testing of various CKEditor 5-related repositories, such as ckeditor5-dev or ckeditor5-linters-config.

# Setup

In order to use the tool, install it globally from the npm.

npm install -g mrgit

Then, put a file named mrgit.json in the root of the ckeditor5 repository. This is an example content of this file:

    "packages": "external/",
    "dependencies": {
        "ckeditor5-linters-config": "ckeditor/ckeditor5-linters-config@latest",
        "ckeditor5-dev": "ckeditor/ckeditor5-dev@latest"
    "presets": {
        "dev": {
            "ckeditor5-dev": "ckeditor/ckeditor5-dev"
        "example-feature": {
            "ckeditor5-linters-config": "ckeditor/ckeditor5-linters-config#i/1-example-feature",
            "ckeditor5-dev": "ckeditor/ckeditor5-dev#i/1-example-feature"

Support for tags and presets is available since mrgit v2.0.0+.

# Usage

In the example configuration file listed above we have defined base dependencies that should be used. These use the @latest tag, which means that the latest release tag will be used, which generally should coincide with the latest version available on npm. After calling mrgit sync, these dependencies will be cloned and made available locally in the specified (latest) version.

Alternatively, you can use one of the presets defined in the latter section of the file, eg. the dev preset. To do so, execute mrgit sync --preset dev – this will use versions specified in the preset instead. ckeditor/ckeditor5-dev does not have any tag or branch specified, so the master branch will be used by default.

Since only ckeditor5-dev is specified in this preset, version used for ckeditor5-linters-config will be the same as specified in the default dependencies section. Using this mechanism, it is possible to easily switch between production and development versions of the dependencies used by the ckeditor5 repository.

For all available commands and configuration options, see the Mr. Git documentation.

# Testing helpers

The getData() and setData() functions exposed by model developer utilities and view developer utilities are useful development helpers.

They allow for “stringifying” the model and view structures, selections, ranges, and positions as well as for loading them from a string. They are often used when writing tests.

Both tools are designed for prototyping, debugging, and testing purposes. Do not use them in production-grade code.

For instance, to take a peek at the editor model, you could use the getData() helper:

import { getData } from '@ckeditor/ckeditor5-engine/src/dev-utils/model';

// More imports.
// ...

    .create( '<p>Hello <b>world</b>!</p>' )
    .then( editor => {
        console.log( getData( editor.model ) );

        // -> '<paragraph>[]Hello <$text bold="true">world</$text>!</paragraph>'
    } );

See the helper documentation to learn more about useful options.

# Package generator

For a quick jump start on development of a plugin, use the CKEditor5 Package Generator.

See the documentation to learn more.