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CKEditor 5 is a project that allows you to quickly and easily initialize one of the many types of editors it offers in your application. At the same time, it is a framework for creating custom tailored rich text editing solutions. The former requirement is met thanks to CKEditor 5 Builds. The latter — thanks to CKEditor 5 Framework.

This guide explains how the framework is built and how to start using it.

# When to use the framework?

CKEditor 5 Builds can be customized, but certain types of customizations require using the framework.

  • Writing your own features. Features are implemented using the framework.
  • Customizing existing features. Changing the behavior or look of existing features can be done using the framework capabilities.
  • Creating new types of editors. You can create new types of editors using the framework.

To sum up: you need to start using the framework as soon as existing builds do not meet your requirements or cannot be customized to the extent you want.

# Design

The framework was designed to be a highly flexible and universal platform for creating custom rich text editing solutions. At the same time it meets several goals that make implementing features as easy a task as possible.

  • Plugin-based architecture. Everything is a plugin — even such crucial features as support for typing or <p> elements. You can remove plugins or replace with your own implementations to achieve fully customized results.
  • Universal core. The core makes minimal assumptions and can be controlled through the schema. This leaves all decisions to plugins and hence to you.
  • Collaboration-ready editing engine. The editing engine implements Operational Transformation algorithms which, accompanied with additional mechanisms, allows to implement real-time collaboration.
  • Custom data model. The editing engine implements a custom data model, designed to best fit multiple requirements such as enabling real-time collaboration and complex editing features.
  • Virtual DOM. The editing engine features a custom, editing-oriented virtual DOM implementation that aims to hide browser quirks from your sight.
  • Granular, reusable features. Features are implemented in a granular way. This allows for reusing and recomposing them which, in turn, makes it possible to customize and extend the editor. For instance, the image feature consists of over 10 plugins at the moment.
  • Extensibility. The entire editor architecture was designed for maximum flexibility. The code is event-based and highly decoupled, allowing you to plug in or replace pieces that you want to change. Features know minimum about themselves and communicate in standardized ways.
  • Quality. All official packages have extensive tests suites (100% code coverage is merely a step to that). All code has extensive API documentation.
  • Minimal configuration. To avoid bloat, features have minimal configuration. Deeper changes in their behavior can be done by recomposing them with custom features.

# Framework structure

The framework is made of several npm packages. Every package is developed in its own repository, making CKEditor 5 a multi-repository project. The main repository that glues all of them and contains CKEditor 5 development environment is

The full list of official packages which make the framework is available in the main repository’s README.

There are a few groups of packages:

  • Core libraries – A set of packages which are the root of the framework.
  • Editors – Packages that implement various types of editors.
  • Features – Packages that implement end user features.
  • Themes – Packages that implement editor themes.
  • Builds – Packages containing CKEditor 5 Builds.

# What’s next?

To start using the framework refer to: