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Kloudless File Picker

Sign up for a free account at to obtain a Kloudless App ID to initialize the File Picker with. The File Picker is built on our unified Storage API abstraction layer (Cloud Storage REST API docs here).

The Kloudless File Picker is a JavaScript library that allows your users to browse and select files and folders from the following storage services:

Adobe CQ5Alfresco CloudAlfrescoAmazon S3
Azure StorageBoxCMISCitrix Sharefile
Google DriveHubSpot FilesJiveOneDrive for Business
OneDriveSMBSalesforce FilesSharePoint Online

Click here to visit our File Picker demo!

Table of Contents


Initializing a File Picker

The File Picker JavaScript library can be imported into web applications and launched when a user clicks an element.

Import from a script tag

Include the Kloudless File Picker JavaScript library on your HTML page using a script tag that points to our CDN:

<script type="text/javascript"

This exposes a global Kloudless.filePicker object you can use to initialize a File Picker. Check out the Configuration Options section further below for a full list of configuration options.

<script type="text/javascript">
  var picker = window.Kloudless.filePicker.picker({
    // File Picker initialization options here.
    app_id: "Your App ID", // Get your own at

Import from an ES6 module

You can also install the File Picker package from NPM:

npm install @kloudless/file-picker
import filePicker from '@kloudless/file-picker';

const picker = filePicker.picker({
  app_id: "YOUR_APP_ID"

Launching the File Picker

Here is a basic example of a button that launches the File Picker given the JavaScript above that creates a picker object.

  <button id="choose-files">Choose Files</button>

  <script src=""></script>
    var picker = window.Kloudless.filePicker.picker({ app_id: "APP_ID" });

The HTML above adds a specific id to an element so that we can reference it later in our JavaScript that launches the File Picker when the element is clicked. A more complete example is present below after the full list of configuration options as well as on our demo page.

Be sure to serve the page via a web server, as pages opened via the file URI scheme (file://) cannot receive postMessage messages from the iframe created to display the File Picker due to security concerns.

File Picker Modes

The File Picker can be configured to either be a file chooser to select files and folders from cloud storage or the local computer, or a file saver to export a specific file to cloud storage.


The Chooser allows your application to prompt a user to select files or a folder, and retrieves metadata about the files or folder selected. It supports choosing files from the local machine as well as cloud storage. Your application can also upload files to users' cloud storage using the Upload API endpoint after prompting users to select a folder to upload data to.

The Chooser is therefore a popular option for both importing files to your application as well as exporting them to specific destinations in cloud storage.


The Dropzone is a variety of the Chooser that opens when files are dragged and dropped into it rather than only when clicked. See the Dropzone section for more information.


The Saver allows your application to prompt a user to select a folder to save a specific file to. This lets your application save some work over the Chooser by automatically handling the upload to cloud storage given a link to the file. However, only a single file is supported at a time.

The Saver returns metadata on the newly uploaded file to the application.


The File Picker has several configuration options. Below, we've included options that can be set on the library inclusion tag itself, options that apply to both the Chooser and Saver modes, and options that are specific to a particular mode.

Script tag

The following attributes can be set on the <script> tag used to include the File Picker JavaScript on the page.

  • data-kloudless-object : string

    Optional. By default, the filePicker object will be exposed to window.Kloudless.filePicker.

    Specifies a different name for the filePicker object bound to window. e.g. data-kloudless-object="filePicker2" would make the filePicker object accessible via window.filePicker2. Do not use the async attribute on the script tag if this is used.

Chooser and Saver

  • app_id : string

    Chooser: Required

    Saver: Required

    The application ID is specific to the developer's application and is located in the developer portal on the App Details page.

  • element : string or HTMLElement

    Chooser: Optional (default: null)

    Saver: Optional (default: null)

    Specify a CSS selector string or DOM element to attach the File Picker to instead of displaying the File Picker as a modal (the default). If a string is provided, it will be used to retrieve the DOM element by using document.querySelector.

  • retrieve_token : boolean

    Chooser: Optional (default: false)

    Saver: Optional (default: false)

    This option will include Bearer Tokens in addition to the other response data, to allow you to make further requests to the API or save the OAuth Tokens for future use.

    // Example response with an OAuth Token in the metadata.
      bearer_token: {
        key: "the_token",

    Only File Pickers launched from Trusted Domains can make use of this option. You can add a Trusted Domain on the App Details page.

    In addition, care should be taken to ensure no malicious JavaScript or XSS vulnerabilities are present on the page, as the Bearer Token provides complete access to that user's account.

  • persist : string

    Chooser: "none", "local", "session" (default: "local")

    Saver: "none", "local", "session" (default: "local")

    This option specifies how to persist connected account information, such as Bearer tokens to access the Kloudless API.

    The File Picker will fall back to local if an invalid option is specified, and fall back to none if either localStorage or sessionStorage are not accessible.

  • services : array

    Chooser: Optional (default: ['file_store'])

    Saver: Optional (default: ['file_store'])

    This option specifies which services to allow a user to explore. You can enumerate the specific services or use a service group listed below as a shortcut. The default is the file_store service group. If you specify an empty array, no services will show up.

    Service groups:

    • file_store: All File Storage services.
    • object_store: All Object Storage services.
    • construction: All Construction services.
    • all: All storage services.
  • account_management : boolean

    Chooser: Optional (default: true)

    Saver: Optional (default: true)

    If false, hides the Account menu entry in the dropdown. This can be combined with the tokens option to ensure a user only browses a pre-defined list of accounts and also does not disconnect any of the accounts. If account disconnection is permitted, set services to [] rather than disabling the account_management option.

  • display_backdrop : boolean

    Chooser: Optional (default: false)

    Saver: Optional (default: false)

    If true, displays a shadow backdrop behind the File Picker, and prevents the page body from scrolling.

  • locale : string

    Chooser: Optional (default: "en")

    Saver: Optional (default: "en")

    The Kloudless File Picker supports i18n/l10n. You can specify any of the following ISO-639-1 codes:

    ar, az, bs, cs, cy, da, de, el, en, es, et, fa, fi, fr, he, hr, hu, hy, id, it, ja, ka, kk, km, ko, lt, lv, mn, ms, nl, pl, pt, ro, ru, sk, sq, sr, sr, sv, th, tr, uk, zh-CN, zh-TW

    The locale is used to identify the data to retrieve from either the data provided in the translations option below or from the out-of-the-box translation data in the messages directory. If no translation data is found, the File Picker uses the en locale.

  • translations : string or object

    Chooser: Optional (default: "")

    Saver: Optional (default: "")

    This option specifies either an object with translation data or a URL that returns the translation data as a JSON string. The locale option indicates which locale's translation data to use. Any translation data provided here overrides Kloudless' default translation data included in the messages directory. See translations-suite-sample.json for an example of the translation file format. Any strings not translated will default to the en locale's representation.

  • dateTimeFormat : string

    Chooser: Optional (default: "MMMdHm")

    Saver: Optional (default: "MMMdHm")

    This option specifies a date-time format for the locale above. Please refer to the skeleton values in the globalize JS module for the formats supported.

  • create_folder : boolean

    Chooser: Optional (default: true)

    Saver: Optional (default: true)

    If true, the user will be able to create folders in their cloud storage accounts.

  • account_key : boolean

    This option is deprecated as OAuth 2.0 Tokens are used to authenticated accounts now instead of Account Keys. Please use the retrieve_token option below instead. Existing Account Keys can be converted to OAuth Tokens using this endpoint.

  • keys : array

    This option is deprecated as OAuth 2.0 Tokens are used to authenticated accounts now instead of Account Keys. Please use the tokens option below instead. Existing Account Keys can be converted to OAuth Tokens using this endpoint.

  • tokens : array

    Chooser: Optional (default: [])

    Saver: Optional (default: [])

    This option should list OAuth 2.0 Tokens for accounts the File Picker should be initialized with. The File Picker will make API requests for additional information on the accounts and display them in the list of accounts the user has connected.

      tokens: ["abcdefghijklmn", "opqrstuvwxyz"],
      ... // other options
  • enable_logout : boolean (default: true)

    If true, allows users to log out of their accounts, which deletes the account from Kloudless servers. API requests will no longer be possible to the account.

  • delete_accounts_on_logout : boolean (default: false)

    If false, the File Picker only removes tokens from the storage configured in persist option when users log out. If true, it also deletes the accounts from the Kloudless server and invalidates the OAuth tokens.

  • oauth : function (default: see below)

    Use this parameter to customize the query parameters used in the first leg of the Kloudless OAuth flow when authenticating users. A full list of parameters supported is available on the OAuth docs.

    By default, the scope the File Picker uses is "<service_id> <service_id>:normal.basic". Note that the following options cannot be overridden for consistency or security reasons:

    • client_id,
    • response_type
    • redirect_uri
    • origin
    • state

    Set the value of the oauth option to a function that accepts a string. The function will be called when a user attempts to connect an account, with the string argument being the identifier of the service the user is attempting to connect. For example, gdrive.

    The function should return an object representing the attributes to include as query parameters in the OAuth flow. Don't URL-encode the values; the File Picker handles that. Here is an example that customizes the OAuth permissions requested if a user attempts to connect a Google Drive account, and also pre-fills the server URL if a user chooses to connect an FTP account:

      oauth: (service) => {
        const authOptions = {};
        switch (service) {
          case 'gdrive':
            // Ask for read-only access to Google Drive data instead.
            authOptions.scope = '"":raw';
            // Pass additional query parameters to Google Drive.
            authOptions.raw = {
              'query_name': 'query_value'
          case 'ftp':
            // Set a default domain when connecting an FTP account.
            authOptions.form_data = {
              domain: 'ftps://',
        return authOptions;
      ... // other options

    If you're familiar with the configuration options accepted by the Kloudless Authenticator, the File Picker requires options returned in the same format that the Authenticator accepts. For convenience, the following supported parameters can be specified as objects as shown in the example above:

    • form_data (converted to a URL-encoded JSON string)
    • custom_properties (converted to a URL-encoded JSON string)
    • raw (converted to the raw[key]=value format described in the docs)
  • custom_style_vars : object

    This project uses LESS as a CSS pre-processor. Since LESS can be run in the browser, we support overriding CSS global variables dynamically to customize styling. For example, change the primary color by setting main_color:

      custom_style_vars: {
        main_color: "black"

    Please refer to variables.less for the full list of available variables. Most are related to aspects such as colors, fonts, or dimensions. Specifying the @ prefix for each variable is optional.

    For further customization, we recommend forking this project and hosting the resources on your own, since we don't guarantee backward-compatibility when overriding undocumented variables.

  • root_folder_id: object

    Chooser: Optional (default: {})

    Saver: Optional (default: {})

    This option is used to specify a specific folder as the root folder for any existing account browsable via the File Picker. This is helpful for scenarios where the user may not have access to the root or other high-level folders but does have access to specific known folders within the account. This option accepts a map of the Kloudless Account ID to the Kloudless Folder ID in the format {[account_id]: "root_folder_id"}, as shown below:

      1234: "folder_abc1234",
      5678: "folder_somefolder5678"

    The example above sets the root folder to folder_abc1234 for account 1234 and folder_somefolder5678 for the account 5678.

    When connecting or switching to an account that has a root folder ID configured, the default folder opened will be the specified folder rather than the usual root folder root. The File Picker UI won't enable navigation outside of the chosen root folder, although it may be accessible to the user via direct API requests. This configuration option should therefore not be used to limit access for security purposes.

    For existing accounts, be sure to also use the tokens attribute to specify the Bearer tokens to use to browse the account. If account_management is enabled (the default), the user may also connect new accounts. Since the root folder ID is not possible to provide in advance until the newly connected account's ID is known, please first listen for the addAccount event, then perform API requests to determine the ID of the root folder to display, and finally call the picker.update() method with the updated configuration that includes the root folder ID for the newly connected account within it:

    let root_folder_id = {}; // Any existing root folder IDs
    picker.on('addAccount', account => {
      // Set `retrieve_token: true` in the config to retrieve the Bearer token
      // to use in API requests to determine the right root folder ID, and
      // then include that root folder ID below.
      root_folder_id[] = 'root';
      picker.update({ root_folder_id });

    Here is an example of limiting users connecting SharePoint accounts to only selecting files from within the primary document library of the main site collection:

    The example above uses a known folder ID based on a consistent location within the SharePoint tenant, but most folders' IDs are random and must be obtained dynamically. To obtain the Kloudless Folder ID for an upstream folder path, please use the Encode Raw Data API endpoint or list the contents of the account, beginning at the root, until the required folder's metadata is obtained.

    Note: Search requests may still return results outside the root folder specified for services that do not support the parents query parameter.

  • close_on_success : boolean (default: true)

    Defaults to true, which closes the File Picker when all the selections in the Chooser have been processed successfully, or when all the files in the Computer view or the Saver have been uploaded successfully.

    If false, the user will see a success message rather than the File Picker closing.

    For the Chooser and the Saver, if the element option is specified, this option will always be false. For the Dropzone, this option is always true.

Chooser Options

  • multiselect : boolean

    Chooser: Optional (default: false)

    This option allows a user to select multiple files or folders from cloud storage or their local device. The Chooser will return a list of one or more entries. Selecting multiple folders is not currently supported on mobile devices.

  • computer : boolean

    Chooser: Optional (default: false)

    Dropzone: Always true

    This option allows users to upload files directly from their computer. Note: If you plan to build and host the file-picker on your own, this option is only available for the AGPL build.

    Configuring the Chooser's Upload Location

    The Chooser will upload files to the developer's Upload Location. The Upload Location can be set in the developer portal. Under 'UI Tools' tab, click 'File Picker' and follow the instructions for selecting a folder in a storage service such as Amazon S3. All local files from a user will be uploaded there.

  • link : boolean

    Chooser: Optional (default: false)

    If true, generates a link to the selected file(s). The link will be provided in the link key of the response sent to the success event. For asynchronous requests, the result of the Kloudless Task will contain the link instead.

    Use with the copy_to_upload_location option to generate a link to the newly copied file.

    The Kloudless File Picker will fire the error event if the link generation fails.

    // Success event result when `link` is true:
      "link": "https://<the file link>",
  • link_options : Object

    Chooser: Optional (default: {})

    The link_options object provides parameters to use when the File Picker creates links. See the documentation for creating links for a full list of the possible options available. Note that links to selected files are only created if the link configuration option is set to true. In addition, files with the downloadable attribute set to false cannot be downloaded so they cannot be selected if is true.

    For example:

      link_options: {
        direct: true,
        expiration: "2020-10-12T00:00:00"
      ... // other options
  • copy_to_upload_location : string

    Chooser: Optional (default: null)

    If this option is set, it will copy any file or non-root folder selected by the user from cloud storage to the location that files uploaded from the user's computer are placed in.

    Since the file must be able to be downloaded for this to occur, only files with the downloadable attribute set to true can be selected when this option is enabled. When copying folders, the non-downloadable files will be skipped.

    An Upload Location must be configured via the developer portal to make use of this option.

    This option accepts two values:

    • 'async': Triggers an asynchronous copy and immediately returns a Task ID in the success event callback that can be checked using the Kloudless Task API for the copied file or folder's metadata.

      The Kloudless Task API returns a Task object that includes progress information until the task finishes.
      When the task finishes, the API endpoint returns File or Folder object instead.
      If the task fails, the endpoints returns an Error.

      Here is an example of polling for the result of a task using jQuery:

        function pollingTask(taskId, accountToken, delay) {
          return new Promise((resolve, reject) => {
            setTimeout(() => {
                url: `${taskId}`,
                headers: { Authorization: `Bearer ${accountToken}` },
            }, 5000);  // Poll every 5 seconds
        picker.on('success', async (results) => {
          // Assume the user only selects one item.
          const [
              id: taskId,
              // Should enable `retrieve_token` option to get bearer_token.
              bearer_token: { key: accountToken },
          ] = results;
          try {
            let response = await pollingTask(taskId, accountToken);
            while ( === taskId) {
              // Task has not finished yet, so keep polling.
              response = await pollingTask(taskId, accountToken);
            // Task has finished.
          } catch (jqXHR) {
            if (jqXHR.responseJSON) {
              // Kloudless API Server returned an error.
    • 'sync': Triggers a synchronous API request to copy the file or folder and polls till the copying is complete. The success event callback receives the newly uploaded file or folder's metadata.

    The deprecated true option is only available for copying files and will return the new file's hypothetical metadata even though the copy has not yet completed. Please migrate to using 'sync' instead for similar behavior with a guarantee that the copy is successful.

    The Kloudless File Picker will fire the error event if the copy operation is not completely successful.

  • upload_location_account : string

    Chooser: Optional (default: null)

    If multiple Upload Locations are configured via the developer portal, this specifies the Account ID of the Upload Location to use. This option is not required if only one Upload Location is configured. The Account ID is a number that can be found in the File Picker Upload Locations section of the Developer Portal page. upload_location_folder must also be provided.

  • upload_location_folder : string

    Chooser: Optional (default: null)

    If multiple Upload Locations are configured via the developer portal, this specifies the Folder ID of the Upload Location to use. This option is not required if only one Upload Location is configured. The Folder ID is an encoded string that can be found on the File Picker Upload Locations section of the Developer Portal. The ID of a sub-folder may be specified if the option is enabled in the Developer Portal. upload_location_account must also be provided if more than one upload location exists.

  • uploads_pause_on_error : boolean

    Chooser: Optional (default: true)

    If true, uploads using the Computer option will pause if errors are encountered, giving the user the option to retry the upload by clicking 'Resume'. The user could also remove the file that is failing to upload from the queue. If false, the file that encounters errors will be skipped and excluded from the list of files returned in the success callback.

  • types : array

    Chooser: Default: ['all']

    This option specifies which types of elements the File Picker will show to the user. You can filter based on file extension or by the following categories:

    • all This configures the File Picker to show all file types and folders. The user can select either files or folders. Do not combine with other options.

    • folders This configures the File Picker to gray out files and show folders. The user can only select folders.

    • files This configures the File Picker to show all file types. The user can only select files.

    • text

    • documents

    • images

    • videos

    • audio

The categories will be translated to the corresponding file extensions and MIME types internally. Check TYPE_ALIAS and MIME_TYPE_ALIAS in constants.js for the specific file extensions and MIME types mapped to.

You can also specify file extensions as well as MIME types by including them in the array without the period (.) prefix. For example, ['pdf', 'jpg', 'jpeg', 'png', 'application/'].

Include '' to allow files with the MIME type application/octet-stream or without a file extension to be selected.

  • max_size : number

    Chooser: Optional (default: 0)

    The maximum size (in bytes) of files that can be selected, or uploaded in the case of local uploads via the Computer option. This limit applies per file selected, and not collectively.

    Set to 0 to disable this limit.

    Files with an unknown size, such as Google Docs, can still be selected regardless of this option.

Saver Options

  • files : array

    Saver: Optional (default: [])

    This option should list files for the File Picker to save. The format should be an array of Javascript Objects containing a file url and name. You can specify up to 100 files. Each file will be uploaded via the Kloudless API's upload endpoint, using the url attribute.

      files: [{
        url: "http://<your image url>",
        name: "filename.extension"
      }, {
        url: "http://<your image url>",
        name: "filename.extension"
      ... // other options


  • success(results)

    Fired when the user's selections in the Chooser are processed successfully, or files are uploaded successfully via the Chooser's Computer option or Saver.
    The success event is still fired even if only part of the items were successfully chosen or saved.

    results is an array of File or Folder objects that were successfully selected.

    When copy_to_upload_location is set to async, results will instead be an array of Task objects returned by the Kloudless Task API.

    The File Picker closes once this event has triggered.

  • cancel()

    Fired if the user decides to cancel an operation. The File Picker will be closed on cancellation.

  • error(results)

    Fired when any of the selections fail to process or any of the files being uploaded fail to upload successfully.
    The error event is still fired even if only part of the items failed to be chosen or saved.

    results is an array of failed objects. The object structure varies based on usage. For the selections in the Chooser, the object is a File or Folder object.

    For uploads via the Chooser's Computer option or Saver, the object is the same as that for the startFileUpload event mentioned below.

    An additional key, error, is added to the object metadata and includes the error returned from the Kloudless API describing why the operation failed.

    Here is an example of the error object:

      "status_code": 404,
      "message": "File not found: 1D-QuGwx7acbeGQ3STSCphysJsQs8YHJR",
      "error_code": "not_found",
      "id": "9b62d9d8-7bc7-495b-b97a-33b43720274d"
  • open()

    Fired when the File Picker is displayed to the user. This occurs when the Chooser or Saver are opened.

  • close()

    Fired when the File Picker is hidden from the user. This occurs when the File Picker is closed. This could be due to either a user action, such as choosing files or cancelling, or due to the close() method being called (not to be confused with this close event handler). The success or cancel events will also be fired if appropriate.

  • selected(results)

    Fired when the user selects files or folders from the File Picker, but before the list is sent to the Kloudless API for additional processing. This means this event fires before the success event, and allows you to perform any action while waiting to get the final list.

    If copy_to_upload_location and link are both disabled, then this event is equivalent to the success event (since nothing needs to happen on the server after the selections are made), so this event serves no purpose then.

    results is an array of File or Folder objects.

    This event is not fired when the user uses the Chooser's Computer option or the Saver. See startFileUpload and finishFileUpload for events fired in those cases.

  • addAccount(account)

    Fired when a user successfully connects an account. account is an object containing the account ID, name, and service ID.

    Here is an example:

      "id": 123456,
      "name": "",
      "service": "gdrive"
  • deleteAccount(accountId)

    Fired when a user successfully removes an account.

  • startFileUpload(file)

    Fired when a file upload starts, or is requested to be retried by a user after encountering errors (see the uploads_pause_on_error option). This event is only fired when the user uploads a file via the Chooser's Computer option or the Saver.

    For the Chooser's Computer option, the file object has the following attributes:

    • id A randomly generated ID.
    • name The uploaded file's name.
    • size The uploaded file's size.
    • mime_type The uploaded file's MIME type.

    Here is an example:

      "id": "o_1efeta5ej5ac1v4t139e39l1ldka",
      "mime_type": "image/jpeg",
      "name": "15224125762.jpeg",
      "size": 9834

    For the Saver, the file object has the following attributes instead:

    • url The file URL specified in the Saver's launch options.
    • name The file name specified in the Saver's launch options.

    Here is an example:

      "url": "",
      "name": "kloudless-logo.png"

    This event is fired once per file and not per uploaded chunk.

  • finishFileUpload(file)

    Fired when a file upload completes successfully (once per file being uploaded). The file object contains the same information as provided to the startFileUpload event above, with an additional key metadata whose value is the resulting File.

    This event is only fired when the user uploads a file via the Chooser's Computer option or the Saver.

  • logout()

    Fired when the user clicks the logout link in the File Picker, which clears the local state of accounts connected to the File Picker.

  • drop()

    Fired when drops files into Dropzone.


  • filePicker.picker(options)

    You can initialize a Kloudless File Picker using the options mentioned above.

  • filePicker.getGlobalOptions()

    Get build options. These are options configured when the File Picker JavaScript library was initially built. See the Self-Hosting section for more information.

  • filePicker.setGlobalOptions(buildOptions)

    Change build options during run-time. The widget is configured to work with default values, so these options should only be set when needed.

  • picker.choose()

    This method allows you to launch a Chooser.

  • picker.choosify(element)

    This method binds a click handler that launches the Chooser to the DOM element.


    This method allows you to launch a Saver. See Saver Options for more information on the format for files.

  • picker.savify(element, files)

    This method binds a click handler that launches the Saver for files to the DOM element.

  • picker.on(event, callback)

    Invokes a callback method on a particular event. See the Events section above for a list of event names, as well as the arguments the corresponding callback methods will be invoked with.

  • picker.close()

    This method closes the File Picker window.

  • picker.update(options)

    Updates the configuration options the File Picker was initialized with. The File Picker will immediately begin using the new configuration. options is an Object with the new configuration. Not all options can be updated in this manner. The following are not supported:

    • app_id
    • types
    • services
    • persist
    • create_folder
    • account_key
    • custom_style
    • custom_css (deprecated)
    • locale
    • element
    • max_size
  • picker.logout(deleteAccount=false)

    Removes all authentication tokens for the accounts connected to the File Picker as configured via the persist option. If deleteAccount is set to true, it also deletes the accounts from the Kloudless server and invalidates the OAuth tokens, rendering them unusable and the accounts inaccessible.

    This method isn't impacted by the delete_accounts_on_logout option.

  • picker.destroy()

    Destroy the file picker instance. It includes closing the file picker, removing the EventListener, and removing the DOM including the file picker iframe.

    This method won't clean up localStorage/sessionStorage, so the authentication tokens won't be removed.

Script tag example

To start using the File Picker, simply include the JavaScript file in your HTML file. You can then create an element on the page to launch the File Picker.

  <button id="file-picker-button">Open File Picker</button>
  <script type="text/javascript" src=""></script>
  <script type="text/javascript">
      // File Picker initialization JS here.

The next step is to customize the File Picker according to the developer's needs. In this example, we've decided to disable multiselect, return links, and allow for a few types of files. All of this is contained within the initialization.

// File Picker initialization JS
var picker = window.Kloudless.filePicker.picker({
  app_id: 'YOUR_APP_ID',
  multiselect: false,
  link: true,
  types: ['images', 'documents', 'text']

The final step is to launch the File Picker and handle the events returned from the File Picker based on a user's actions.

Visit our demo of the File Picker!

// When a user successfully selects or saves a file
picker.on('success', function(files) {
  // files is an array of JS objects that contain file metadata.
  console.log('Successfully selected files: ', files);

// When a user cancels the File Picker
picker.on('cancel', function() {
  console.log('File selection cancelled.');

// Launching the File Picker to choose when a user clicks the 'Open File Picker'
// button.

// In addition, you can launch the File Picker programmatically with choose()

// Launching the Picker to save when a user clicks the 'Open File Picker' button
// Note: you can pass in an array of files instead of using the configuration
// option
var files = [{
  url: 'http://<your image url>',
  name: 'filename.extension'
}, {
  url: 'http://<your image url>',
  name: 'filename.extension'

picker.savify(document.getElementById('file-picker-button'), files);

// In addition, you can launch the File Picker programmatically with save()
var files = [{
  url: 'http://<your image url>',
  name: 'filename.extension'
}, {
  url: 'http://<your image url>',
  name: 'filename.extension'


The Dropzone is a variety of the Chooser that allows users to drop files into it from their Computer rather than only click on it to launch the File Picker. It opens in place when files are dropped into it.

Note: If you plan to build and host the file-picker on your own, the Dropzone is only enabled for the AGPL build.


The configuration is similar to the Chooser's, but requires the element option to indicate where to display the Dropzone, as described below. In addition, the computer option is always set to true, and an Upload Location must be configured as described for the Chooser.

  • element : string or HTMLElement

    Chooser: Required

    The DOM element to bind the Dropzone to. If a CSS selector string is provided, it will be used to retrieve the DOM element by using document.querySelector. The drop zone will render a 600px * 100px area for the user to drag and drop files in. The area's width will adjust automatically when the viewport width is lower than 600px.


  • filePicker.dropzone(options)

    Initialize a Dropzone using the options mentioned above.

  • dropzone.on(event, callback)

    See picker.on(event, callback) for more information.

  • dropzone.close()

    See picker.close() for more information.


Visit our JSBin example of the Dropzone!


<div id="dropzone" style="width: 600px; height: 100px;"></div>


var dropzone = window.Kloudless.filePicker.dropzone({
  app_id: 'Your App ID',
  element: '#dropzone',
  multiselect: true, // To upload more than 1 file.

  // Chooser options below:
  computer: true,
  link: true,
  services: ['all'],
  types: ['all'],

// All of the Chooser's events are supported.
// For example:
dropzone.on('success', function(files) {
  console.log('Successfully selected files: ', files);

// See the File Picker's Example section for other events.

File Picker with Vue

See File Picker with Vue.

File Picker with React

See File Picker with React.

Browser Support

  • Chrome 56+
  • Firefox 56+
  • IE 11+
  • Edge 12+
  • Safari 8+
  • Opera 49+

Work with mobile devices

To use the Kloudless File Picker on devices with narrow screens, please add a Viewport meta tag to the web page launching the File Picker. This ensures the File Picker uses styling appropriate for mobile screen sizes.

The meta tag assumes that your entire web page renders well in narrow screens since it applies to your page as a whole and not just the File Picker. Please test out your page's usability if you are adding the meta tag for the first time.

Here is an example meta tag:

<meta name="viewport" content="width=device-width, initial-scale=1">

If your page benefits from preventing some devices such as iPhones from zooming in on input fields, you can also add in the user-scalable=no option as shown below. Input fields such as <input> and <select> are used in the File Picker as well.

<meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">

Migration Guide

From v1 to v2

New Layout and New Options to Customize the UI

v2 represents a new layout and set of options for the File Picker, including:

  • A completely new theme for the UI with improved responsiveness, clearer HTML and CSS structure with consistent naming conventions, and several bug-fixes.
  • A documented format for customizing UI styling such as colors and fonts without forking the entire project.

Provided your application isn't already customizing styling by using the custom_css option as detailed below, it will automatically begin using the new version.

File Explorer Renamed to File Picker

The File Explorer has been renamed to the File Picker to improve clarity. The entire JS namespace, as well as any relevant method, variable, or configuration option names, have been transitioned from referencing an "explorer" to a "picker", while preserving backwards-compatibility.

Here is a table to assist with transitioning previously publicly documented names to their newer counterparts:

Description Old Name New Name
namespace window.Kloudless.fileExplorer window.Kloudless.filePicker
method explorer() picker()
global option explorerUrl pickerUrl
environment variable EXPLORER_URL PICKER_URL
script tag URL

Forked projects that are migrating to v2 should take care to replace names similarly.

React and Vue Wrapper Options Configuration

Previously, getGlobalOptions and setGlobalOption were imported from @kloudless/file-picker as shown below:

import filePicker from '@kloudless/file-picker';


Now, they can be imported from @kloudless/file-picker/react, or @kloudless/file-picker/vue, depending on the framework in use:

import { setGlobalOptions, getGlobalOptions } from '@kloudless/file-picker/react';
// Or use the following syntax for VueJS:
// import { setGlobalOptions, getGlobalOptions } from '@kloudless/file-picker/vue';


Incompatible Configuration Options

Below are some options that will no longer be effective, or will force the previous version to continue to load instead, to maintain compatibility.

  • custom_css : string

    Chooser: Optional (default: null)

    Saver: Optional (default: null)

    This option is deprecated and no longer supported in the latest versions of the File Picker. Using this option will result in the File Picker reverting to a previous layout that supported this option.

    Refer to the custom_style_vars option to customize styling instead. Alternatively, you may clone this project and self-host it to customize the UI more extensively.

    Previous Notes

    custom_css is an optional attribute that accepts a URL to a stylesheet for the File Picker to load to override or customize styling. Supports (http|https)://, //, and /path/to.css formats.

    To use the custom_css option, the domain the File Picker is launched from must be added to the application's list of Trusted Domains.

From v1.0.0 to v1.0.1

When using the script tag, the target exposed has been updated from window.Kloudless to window.Kloudless.fileExplorer to better scope our UI tools. All the exports under window.Kloudless are deprecated and have been moved to window.Kloudless.fileExplorer.


Contributions are welcome and appreciated. We'd love to discuss any ideas you have to improve or extend the File Picker. We recommend contacting us at first for major modifications that you would like merged in so we can offer feedback on its implementation.


Install Node.js (sudo apt-get install nodejs or equivalent)
Make sure you have nodejs >= 10.16.0 and npm >= 6.9.0. Then run the following commands:

npm ci
npm run install-deps

To develop Vue or React wrapper, you might want to install the corresponding storybook:

npm ci --prefix=storybook-vue    # for Vue
npm ci --prefix=storybook-react  # for React


Use the following command to set a Kloudless App ID and run the local development server:

KLOUDLESS_APP_ID=<your_app_id> npm run dev

The File Picker that launches on the test page uses the App ID to connect accounts. It must therefore be the ID of a valid Kloudless Application on the Kloudless API server the File Picker accesses.

By default, the development server points to However, you can point it to an alternate Kloudless API server using the BASE_URL environment variable build option as shown below.

# Export this environment variable before the `npm run dev` command above.
export BASE_URL=<your_kloudless_api_server_url>

The development server supports automatically rebuilding the source files whenever changes are saved. However, hot reloading scripts is not supported yet; you will need to reload the page to view your changes.

TypeScript Definition

Be sure to update src/loader/js/interface.d.ts if the corresponding interface is changed.


The command below generates a minified production build at /dist.

npm run build

Here is an explanation of the dist folder's structure:

Folder Purpose
loader Contains the script that an application includes to load the File Picker.
picker Contains the File Picker assets that the loader loads in an iframe. Only customize this when self-hosting the File Picker.

The above command generates a build licensed under MIT by default. If you want to self-host the File Picker, please note that the Computer option and the Dropzone are only available in an AGPLv3 licensed build. For more details, refer to the License section. To get an AGPLv3 licensed build, run

npm run build:agpl

, or customize your build by providing the build option BUILD_LICENSE=AGPL.

Build Options

The options below can be set during the build process as environment variables to customize the build, or sometimes at run-time as well.

Build-time Env Var Run-time option Description Default
BASE_URL baseUrl URL to the Kloudless API Server
PICKER_URL pickerUrl The URL that the loader loads the file picker iframe from.
BUILD_LICENSE N/A MIT or AGPL. See the Build section. MIT

Check out the Self-hosting section below for an example that changes the PICKER_URL in order to self-host a customized fork of the File Picker.

In addition, here is an example that directs API requests from the File Picker to an alternate Kloudless server:

BASE_URL=<your_kloudless_api_server_url> npm run build


To test the build generated by npm run build, run the following command:

KLOUDLESS_APP_ID=<your_app_id> npm run dist-test

To test the TypeScript definition file, run the following command:

npm run test:ts

Test in Legacy Microsoft Edge or Internet Explorer 11

Microsoft provides Windows 10 virtual machines that can be used to test the File Picker in Legacy Microsoft Edge and Internet Explorer 11. Note that the development server won't be accessible at http://localhost:3000 by default because localhost translates to which points to the VM itself instead of the host running the development server. To work around this, determine the actual IP address of the host running the development server, such as when using VirtualBox, and edit C:\windows\system32\drivers\etc\hosts as an Administrator to add a record that maps localhost to that IP.


Self-hosting the File Picker is one way to customize all aspects of the File Picker's layout, styling, and functionality beyond what the configuration and theming options provide.

You can fork the File Picker to make the changes you need before building the File Picker, which results in a JS file at dist/loader/loader.min.js. This file must be included in any page you would like to use the File Picker on. It serves as a light-weight wrapper to load the actual File Picker page via an iframe.

Both the loader file and the rest of the File Picker's structure are discussed in more detail in the Build section above.

Hosting the File Picker Page

The build contains an picker folder which includes the actual HTML and functionality of the widget. By default, this is hosted by Kloudless.

If you would like to host this page yourself to customize the core File Picker source code or styles, follow the steps below:

  1. Rebuild the assets while setting PICKER_URL to specify the File Picker page URL. For example, if you'd like to host the File Picker assets at, run the following command:

    PICKER_URL= npm run build

    Optionally, you can also set Kloudless.filePicker.setGlobalOptions at run-time instead of re-building the loader:

      pickerUrl: '',
  2. Copy the entire dist/picker folder into your web application's assets so the dist/picker/index.html page can be found at the URL specified in the step above. In the example above, copy dist/picker to /kloudless for to exist.

  3. Add your web app's domain to your Kloudless App's list of Trusted Domains on the App Details Page. This allows the hosted File Picker to receive access tokens to the Kloudless API.

  4. Include dist/loader/loader.min.js in your pages that will launch File Picker as shown in the script tag example above.

Extending the File Picker Template

This section contains advanced concepts that are not usually required in a fork of the File Picker.

The template/picker.ejs template contains necessary styles and scripts for the File Picker as well as the compiled HTML snippets.

Feel free to add additional styles, scripts, or HTML elements you need. You can then run npm run build:template to build your customized File Picker template. The built page will be available at dist/custom-index.html. Replace dist/picker/index.html with this file, and follow the steps in the section above to host this page instead.

For an example, run npm run build:template without any changes and check the result at dist/custom-index.html.

Misc. Development Notes

  • In order to switch folders, we change the current() pointer and then refresh(). refresh() will abort any currently active requests to prevent race conditions
  • Put buttons that can be clicked repeatedly into data-bind clicks instead of the router, because the hash will prevent the route from being fired twice consecutively. Use the hash to switch between pages of the application.

Security Vulnerabilities

If you have discovered a security vulnerability with this library or any other part of Kloudless, we appreciate your help in disclosing it to us privately by emailing


The source code is licensed under the terms of the MIT. Please notice that our library has an optional dependency @kloudless/file-picker-plupload-module, which is licensed under AGPLv3. If you want to build the file-picker on your own, the default build is MIT licensed, which means the file upload module is excluded, and thus the Computer option and the Dropzone are disabled. If you want to make an AGPLv3 build with the @kloudless/file-picker-upload-module, please refer to the Build section. If you want to modify the AGPLv3 licensed build without publishing your source code, please contact us for a commercial license.


Feel free to contact us at with any feedback or questions.