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Custom asset sources

How to add custom asset sources for Sanity Studio.

Sanity Studio comes with a rudimentary asset selector out of the box. It lets you browse and select images or files you have already uploaded. You can also add multiple asset sources, or replace the default one, globally or for a specific asset field.

Asset source plugins

You can find available asset source plugins in the Sanity Exchange or by searching for them on Just like other plugins, asset source plugins are installed using your preferred package manager. Some asset source plugins will require that you add some configuration, for example, an API token.

When adding custom asset source plugins to your studio, the Select button for the upload field will become a drop-down button, showing the multiple sources:

Select image from various asset sources. Here we have installed plugins for Unsplash and Cloudinary.

Defining asset sources globally

Assets sources that are distributed as npm packages usually come with a plugin definition for easy setup.

Let's say you want to add the Unsplash asset source. First, install the plugin by running npm i sanity-plugin-asset-source-unsplash in your project folder. Then, in sanity.config.js, add the following:

import {defineConfig} from 'sanity'
import {deskTool} from 'sanity/desk'
import {unsplashImageAsset} from 'sanity-plugin-asset-source-unsplash'
import {schemaTypes} from './schemas' export default defineConfig({ name: 'default', projectId: '<projectId>', dataset: 'production', plugins: [ deskTool(),
], schema: { types: schemaTypes, }, })

Adding unsplashImageAsset() to the plugins array will deal with registering the asset source and adding it to the list of assets sources for images in your project.

If you want to only allow the Unsplash asset source instead of adding it to the default upload option, you can instead import unsplashAssetSource and add it to form.image as the sole member of the returned array value.

import {defineConfig} from 'sanity'
import {deskTool} from 'sanity/desk'
import {unsplashAssetSource} from 'sanity-plugin-asset-source-unsplash'
import {schemaTypes} from './schemas' export default defineConfig({ name: 'default', projectId: '<projectId>', dataset: 'production', plugins: [deskTool()],
form: {
image: {
assetSources: () => [unsplashAssetSource],
directUploads: false,
schema: { types: schemaTypes, }, })


Many properties of the studio configuration can accept both a static value – an array of asset sources in this case – or a callback function that returns that same value. One crucial difference between the two is that providing a static array of sources will append those sources to the list of existing sources that may have been added by plugins or the studio's default settings, while returning an array of sources from the callback function will replace the current list of sources.

The callback is invoked with the current list of sources as the first argument, so to append to the list when using the callback option you might do something like this: assetSources:(prev)=>[...prev, unsplashAssetSource]

Using sources on a single type

You can customize sources for single image or file type field in the schema via the options.sources property:

  name: 'mainImage',
  title: 'Main image',
  type: 'image',
  options: {
    sources: [unsplashAssetSource],

Remove the Browse option

You can remove the Browse button on an image field (making the field upload-only) by specifying options.sources as an empty array:

  name: 'uploadedImage',
  title: 'Upload an Image',
  type: 'image',
  options: {sources: []}

Anatomy of an asset source plugin

The plugin exports an object with the following shape:

export default {
  name: 'cloudinary', // Unique source name
  title: 'Cloudinary', // Title displayed in lists, buttons etc
  component: Cloudinary, // Selection component
  icon: Icon // Icon for lists, buttons etc.

The selection component

The plugin must define a component that will let the user select some asset(s) from somewhere.

If the user selects something, the component calls the props.onSelect function with an array of asset objects like this:

type AssetFromSource = {
  kind: 'assetDocumentId' | 'file' | 'base64' | 'url'
  value: string | File
  assetDocumentProps?: ImageAsset

An asset can be a URL, user agent File object, base64 encoded binary data or an assetDocumentId. It can have assetDocumentProps that will end up as properties on the resulting asset document. The allowed document props are:

  • originalFilenamestring

    If you would like to use the original filename, when saving the file etc.

  • sourceobject

    {name, id, url?} - Optional object identifying the asset in the source, so you can find all assets from that source, or find it back to the spesific assets when opening the plugin etc. If set, the object properties name and id are required, but url is optional. An example for Instragram images: {name: 'instragram', id: '_cjqbJKwZB', url: ''}

  • titlestring

    Optional title for the asset.

  • descriptionstring

    Optional description for the asset.

  • creditLinestring

    Optional credit line for the asset. E.g. John Doe by Instragram

  • labelstring

    Optional label.

Component Props

  • REQUIREDselectionTypestring

    If the opening interface selection type is 'single' or 'multiple'.

  • REQUIREDselectedAssetsarray

    An array of Sanity assets if they are selected in the opening interface. These are Sanity asset documents.

  • REQUIREDonSelectfunction

    Accepts an array of asset objects (AssetFromSource[])

    When assets are selected and returned to props.onSelect, the Studio will make sure to upload the asset(s). If the selected asset is uploaded previously, the existing asset document and file will be used instead.

  • REQUIREDonClosefunction

    The component must call props.onClose if the select action is canceled or closed somehow.

  • dialogHeaderTitleReact.ReactNode

    A component that serves as the header element for the dialog window.

  • assetTypestring

    Either file or image

Basic component example

The following code shows how to implement a selection component for an asset source plugin. It's not very useful as it will only allow you to pick one very specific image, but it should serve nicely as an example.

import React, {useCallback} from "react";
import {
} from "@sanity/ui";

export default function GitHubAssetSource({ onSelect, onClose }) {
  const handleSelect = useCallback(() => {
        kind: "url",
        assetDocumentProps: {
          originalFilename: "logo-mona.svg", // Use this filename when the asset is saved as a file by someone.
          source: {
            // The source this image is from
            name: "",
            // A string that uniquely idenitfies it within the source.
            // In this example the URL is the closest thing we have as an actual ID.
            id: "",
          description: "Mona Lisa Octocat",
          creditLine: "By",
  }, [onSelect]);

  const handleClose = useCallback(() => {
  }, [onClose]);

  return (
      header="Select image from Github"


CORS headers for image URLs

When calling onSelect with kind: 'url' the resource must respond with a access-control-allow-origin header that allows the image to be read by the Studio host. Using * will allow all hosts (including Studio host).


Best practice

When integrating with an external service, be sure to read the usage guidelines for that service or API. Some will require you to honor the credits for the asset, not expose any API keys etc. Use the assetDocumentProps for onSelect to store any required or relevant information to the resulting asset document. If it is from a service where the asset has an ID and can be displayed in the service, you should use the source key for the assetDocumentProps to store that information. In that way, you can find back to the original asset.

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