An SDK to customize the functionality of the Contentful Web Application Entry Editor.
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Contentful UI Extensions SDK

The UI Extensions SDK allows you to customize and extend the functionality of Contentful Web Application's entry editor. The editor itself is a container for many components that enable editors to manipulate the content stored in content fields. Extensions can be simple user interface controls, such as a dropdown, or more complex micro web applications such as our Markdown editor. They are decoupled entities from field types, and can be reused (for example using a dropdown to edit number or text fields).

Previously, the Contentful Web Application only offered our core platform components to manipulate fields' content. Now, with the UI Extensions SDK it is possible to personalize this Web App based on your needs. Core components and custom extensions are both built on top of the same API, leading them to follow the same approach. The main difference resides in the fact that custom extensions are rendered inside a secure iframe. The next step in our roadmap is to open source our core components to extend them or give more insights on how to build custom extensions.

Every Contentful user has access to this feature, it is enabled by default, and all requirements to start using it are simply to follow the instructions contained here.

This SDK overview introduces you to the concept of custom extensions and lists concrete usage examples. The extension API documentation, on the other hand, provides in-depth information on what the API exposes to the consumer.

You can also refer to the following FAQ for questions related to hosting, or limitations.

Getting started

The most convenient way to upload and manage extensions through our API is via the contentful command line tool. You can install it with

npm install -g contentful-cli

Including the compiled version of the extension client library is as simple as adding the following line to your application.

<script src=""></script>

To get an overview over the API, have a look at the reference documentation.

Check out our example UI Extensions to get a deeper understanding of the SDK's capabilities.

Extensions taxonomy and example use cases

Conceptually, there are two main categories of custom extensions:

  • Single field extensions that reside in the entry editor body and operate on top of a particular field or set of fields.
  • Extensions that reside on the sidebar of the entry editor. They still operate on a particular field but are rendered on the sidebar instead.

Single field extensions

Extensions applied to single fields are great for circumstances where you just want to customize how you edit a particular field type. Examples of single field extensions are:

  • Integration with external digital asset management system (i.e. flickr) to insert external assets
  • Specific data manipulation, like removing an element ID for a social media link
  • Integration with a translation API service to programmatically translate the field's content
  • Creation or integration with custom text editing interface

Multiple field extensions

If you need more than a single field, you can try multi-field level extensions. Currently we have two approaches for this:

Using JSON objects

The first is a simple approach is to use a JSON object field type and construct any complex field type that is not provided out of the box by Contentful, along with its UI and logic. However, there is a tradeoff when using this approach. Data inside of a JSON field cannot be used to query or filter entries in our APIs.

Using relationships between multiple fields

This approach involves creating a single field custom extension that can use our CMA to perform operations on other fields within the entry. Examples of multi-field-level extensions are:

  • Automatic asset metadata creation: When inserting an asset on a media field I want the long-text field below it to query our copyright database and fill-in the details for the asset above
  • Custom recipes: When selecting an item from a dropdown menu I want the content of a short-text field type to change

Sidebar extensions

Sidebar extensions are rendered on the sidebar of the entry editor. They make most sense if the functionality provided by the extension applies to an entire entry instead of a single field.

Examples of sidebar extensions are:

  • Custom webhooks/notifications
  • Integration with a preview environment
  • Moving entries across different spaces

A UI Extension becomes as sidebar extension by setting the property sidebar to true when creating or updating the extension. You can refer to the documentation of the Contentful CLI's extension update command here.

A sidebar extension is still assigned to a field which is then ommited from the entry editor. The field's value can be used to store data for the sidebar extension. If the field should not be distributed to users through the Content Delivery API it can be set to ommited on the content type.

We offer a sample sidebar extension that triggers a build on Netlify

Using Contentful styles

As extensions are rendered inside an iframe, you will need to include the cf-extension.css library within your custom extension in order to use any of Contentful's styles.

You can include this CSS in your extension code as follows:

<link rel="stylesheet" type="text/css" href="">

Futher information about styling your extension can be found in the styleguide.

Providing feedback

Technical feedback can be provided directly through the Github repo. However, if at any point some confidential or business sensitive information needs to be discussed, then the conversation should be handled via our formal support channels.