diff --git a/projects/plugins/debug-helper/changelog/add-jetpack-debug-state b/projects/plugins/debug-helper/changelog/add-jetpack-debug-state
new file mode 100644
index 000000000000..95caaf0a9b91
--- /dev/null
+++ b/projects/plugins/debug-helper/changelog/add-jetpack-debug-state
@@ -0,0 +1,4 @@
+Significance: minor
+Type: added
+
+Add "Cookie State Faker" tool.
diff --git a/projects/plugins/debug-helper/modules/class-cookie-state.php b/projects/plugins/debug-helper/modules/class-cookie-state.php
new file mode 100644
index 000000000000..78d061e713da
--- /dev/null
+++ b/projects/plugins/debug-helper/modules/class-cookie-state.php
@@ -0,0 +1,198 @@
+<?php
+/**
+ * The class allows setting fake cookie states to test the UI.
+ *
+ * @package automattic/jetpack-debug-helper
+ */
+
+namespace Automattic\Jetpack\Debug_Helper;
+
+use Automattic\Jetpack\CookieState as State;
+use WP_Error;
+use WP_REST_Request;
+use WP_REST_Server;
+
+/**
+ * REST_API_Tester to test REST API endpoints.
+ */
+class Cookie_State {
+
+	const REST_BASE = 'jetpack-debug';
+
+	/**
+	 * Allowed state keys.
+	 *
+	 * @var array
+	 */
+	private $keys = array(
+		'error',
+		'error_description',
+		'message',
+	);
+
+	/**
+	 * Construction.
+	 */
+	public function __construct() {
+		add_action( 'admin_menu', array( $this, 'register_submenu_page' ), 1000 );
+		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_scripts' ) );
+		add_action( 'rest_api_init', array( $this, 'register_endpoints' ) );
+	}
+
+	/**
+	 * Register the REST endpoint.
+	 */
+	public function register_endpoints() {
+		register_rest_route(
+			self::REST_BASE,
+			'/cookie-state',
+			array(
+				'methods'             => WP_REST_Server::EDITABLE,
+				'callback'            => array( $this, 'save' ),
+				'permission_callback' => '__return_true',
+				'args'                => array(
+					'key'   => array(
+						'description' => 'The state key.',
+						'type'        => 'string',
+						'required'    => true,
+					),
+					'value' => array(
+						'description' => 'The state value.',
+						'type'        => 'string',
+						'required'    => true,
+					),
+				),
+			)
+		);
+	}
+
+	/**
+	 * Add submenu item.
+	 */
+	public function register_submenu_page() {
+		add_submenu_page(
+			'jetpack-debug-tools',
+			'Cookie State Faker',
+			'Cookie State Faker',
+			'manage_options',
+			'cookie-state',
+			array( $this, 'render_ui' ),
+			99
+		);
+	}
+
+	/**
+	 * Enqueue scripts!
+	 *
+	 * @param string $hook Page hook.
+	 */
+	public function enqueue_scripts( $hook ) {
+		if ( strpos( $hook, 'jetpack-debug_page_cookie-state' ) === 0 ) {
+			wp_enqueue_style( 'cookie_state_style', plugin_dir_url( __FILE__ ) . 'inc/css/cookie-state.css', array(), JETPACK_DEBUG_HELPER_VERSION );
+			wp_enqueue_script( 'cookie_state_script', plugin_dir_url( __FILE__ ) . 'inc/js/cookie-state.js', array( 'wp-api' ), JETPACK_DEBUG_HELPER_VERSION, true );
+
+			add_filter(
+				'script_loader_tag',
+				function ( $tag, $handle ) {
+					if ( 'cookie_state_script' === $handle ) {
+						$tag = str_replace( '<script ', '<script type="module" ', $tag );
+					}
+
+					return $tag;
+				},
+				10,
+				2
+			);
+		}
+	}
+
+	/**
+	 * Render UI.
+	 */
+	public function render_ui() {
+		wp_localize_script(
+			'wp-cookie-state',
+			'wpApiSettings',
+			array(
+				'root'  => esc_url_raw( rest_url() ),
+				'nonce' => wp_create_nonce( 'wp_cookie_state' ),
+			)
+		);
+
+		?>
+		<h1>Cookie State Faker</h1>
+
+		<div class="jetpack-debug-cookie-state">
+			<h2>Current Values</h2>
+
+			<ul class="cookie-state-values-list">
+				<?php foreach ( $this->keys as $key ) : ?>
+					<li><strong><?php echo esc_html( $key ); ?>:</strong> <?php echo esc_html( ( new State() )->state( $key ) ); ?></li>
+				<?php endforeach ?>
+			</ul>
+
+			<h2>Update Values</h2>
+
+			<form method="post" id="jetpack-debug-cookie-state-form">
+				<div class="cookie-state-block">
+					<label for="cookie-state-key">Key:</label>
+					<div class="cookie-state-field">
+						<select name="key" id="cookie-state-key">
+							<?php foreach ( $this->keys as $key ) : ?>
+								<option value="<?php echo esc_html( $key ); ?>"><?php echo esc_html( $key ); ?></option>
+							<?php endforeach ?>
+						</select>
+					</div>
+				</div>
+
+				<div class="cookie-state-block">
+					<label for="cookie-state-value">Value:</label>
+					<div class="cookie-state-field">
+						<input type="text" name="value" class="input-text" id="cookie-state-value" value="">
+					</div>
+				</div>
+
+				<div class="cookie-state-block">
+					<button type="submit" class="button button-primary" id="cookie-state-submit">Save</button>
+				</div>
+
+				<div id="cookie-state-response" class="block-hide"></div>
+			</form>
+		</div>
+		<?php
+	}
+
+	/**
+	 * Load the class.
+	 */
+	public static function init() {
+		new static();
+	}
+
+	/**
+	 * Update the value
+	 *
+	 * @param WP_REST_Request $request The request object.
+	 *
+	 * @return \WP_REST_Response|WP_Error
+	 */
+	public function save( WP_REST_Request $request ) {
+		$params = $request->get_query_params();
+
+		$key = empty( $params['key'] ) ? null : $params['key'];
+
+		if ( ! $key || ! in_array( $key, $this->keys, true ) ) {
+			return new WP_Error( 'unknown_key' );
+		}
+
+		if ( ! array_key_exists( 'value', $params ) ) {
+			return new WP_Error( 'missing_value' );
+		}
+
+		( new State() )->state( $key, $params['value'] );
+
+		return rest_ensure_response( array( 'success' => true ) );
+	}
+}
+
+add_action( 'plugins_loaded', array( Cookie_State::class, 'init' ), 1000 );
diff --git a/projects/plugins/debug-helper/modules/inc/css/cookie-state.css b/projects/plugins/debug-helper/modules/inc/css/cookie-state.css
new file mode 100644
index 000000000000..b8a4f3eb868b
--- /dev/null
+++ b/projects/plugins/debug-helper/modules/inc/css/cookie-state.css
@@ -0,0 +1,60 @@
+/**
+Slyling up the Jetpack State
+ */
+
+.jetpack-debug-cookie-state {
+	margin-top: 20px;
+	float: left;
+	clear: both;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block {
+	margin-bottom: 20px;
+}
+
+.jetpack-debug-cookie-state .cookie-state-field {
+	position: relative;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block label {
+	display: inline-block;
+	font-weight: bold;
+	width: 120px;
+	vertical-align: top;
+	margin-top: 5px;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block .cookie-state-field {
+	display: inline-block;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block select {
+	margin-top: -3px;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block .input-text {
+	width: 100px;
+	height: 35px;
+	font-size: 15px;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block button {
+	height: 35px;
+	width: 80px;
+	cursor: pointer;
+}
+
+.jetpack-debug-cookie-state .cookie-state-block textarea {
+	width: 400px;
+	height: 200px;
+}
+
+.jetpack-debug-cookie-state .block-hide {
+	display: none;
+}
+
+.jetpack-debug-cookie-state #cookie-state-response {
+	margin-top: 30px;
+	border: 4px dashed grey;
+	padding: 10px;
+}
diff --git a/projects/plugins/debug-helper/modules/inc/js/cookie-state.js b/projects/plugins/debug-helper/modules/inc/js/cookie-state.js
new file mode 100644
index 000000000000..6a9460e7c4ce
--- /dev/null
+++ b/projects/plugins/debug-helper/modules/inc/js/cookie-state.js
@@ -0,0 +1,62 @@
+import loaderButton from './loader.js';
+
+class CookieState {
+	constructor() {
+		this.formElement = document.getElementById( 'jetpack-debug-cookie-state-form' );
+		this.keyElement = this.formElement.querySelector( '#cookie-state-key' );
+		this.valueElement = this.formElement.querySelector( '#cookie-state-value' );
+		this.submitElement = this.formElement.querySelector( '#cookie-state-submit' );
+		this.unsetElement = this.formElement.querySelector( '#cookie-state-unset' );
+		this.responseElement = this.formElement.querySelector( '#cookie-state-response' );
+
+		if ( this.formElement ) {
+			this.formElement.addEventListener( 'submit', e => {
+				e.preventDefault();
+				this.submit();
+			} );
+		}
+
+		if ( this.submitElement ) {
+			this.submitElement.addEventListener( 'click', e => {
+				e.preventDefault();
+				this.submit();
+			} );
+		}
+
+		if ( this.unsetElement ) {
+			this.unsetElement.addEventListener( 'click', e => {
+				e.preventDefault();
+				this.unset();
+			} );
+		}
+	}
+
+	async submit() {
+		const loader = loaderButton( this.submitElement );
+		loader.on();
+
+		const key = this.keyElement.value;
+		const value = this.valueElement.value;
+
+		this.responseElement.innerHTML = '';
+		this.responseElement.classList.remove( 'block-hide' );
+
+		const url = `${ window.wpApiSettings.root }jetpack-debug/cookie-state${
+			-1 === window.wpApiSettings.root.indexOf( '?' ) ? '?' : '&'
+		}key=${ encodeURIComponent( key ) }&value=${ encodeURIComponent( value ) }`;
+		const headers = { 'X-WP-Nonce': window.wpApiSettings.nonce };
+
+		const response = await fetch( url, { headers, method: 'POST' } );
+		const body = await response.json();
+
+		if ( body.success === true ) {
+			this.responseElement.innerHTML = 'Saved!';
+			location.reload();
+		} else {
+			this.responseElement.innerHTML = 'Error (see network log)';
+			loader.off();
+		}
+	}
+}
+
+document.addEventListener( 'DOMContentLoaded', () => new CookieState() );
diff --git a/projects/plugins/debug-helper/plugin.php b/projects/plugins/debug-helper/plugin.php
index 4c8988be32e1..714e9e7c5e05 100644
--- a/projects/plugins/debug-helper/plugin.php
+++ b/projects/plugins/debug-helper/plugin.php
@@ -89,6 +89,11 @@
 		'name'        => 'Jetpack Scan Helper',
 		'description' => '',
 	),
+	'cookie-state'       => array(
+		'file'        => 'class-cookie-state.php',
+		'name'        => 'Cookie State Faker',
+		'description' => '',
+	),
 );
 
 require_once __DIR__ . '/class-admin.php';