diff --git a/index.php b/index.php
index d2c2071..dedc302 100644
--- a/index.php
+++ b/index.php
@@ -9,4 +9,135 @@
    Author URI: https://mxstbr.com
    License: MIT
    */
+
+// Inject the feedback.fish JavaScript file into the DOM just before the body
+function enqueue_feedback_fish_script()
+{
+    $projectId = get_option('feedback_fish_project_id');
+    wp_register_script(
+        'feedback-fish',
+        "https://feedback.fish/ff.js?pid=$projectId",
+        [],
+        null,
+        true
+    );
+    wp_enqueue_script('feedback-fish');
+}
+add_action('wp_enqueue_scripts', 'enqueue_feedback_fish_script');
+
+// Add defer="defer" to the feedback.fish <script> tag to avoid blocking render
+// Taken from: https://wordpress.stackexchange.com/a/38335
+add_filter(
+    'script_loader_tag',
+    function ($tag, $handle) {
+        if ('feedback-fish' !== $handle) {
+            return $tag;
+        }
+
+        return str_replace(' src', ' defer="defer" src', $tag);
+    },
+    10,
+    2
+);
+
+// Add "Send feedback" to the primary nav if it exists
+function add_feedback_fish_nav_menu_item($items, $args)
+{
+    $current_user = wp_get_current_user();
+    $manual_usage = get_option('feedback_fish_manual');
+    if (!$manual_usage) {
+        $items .= "<li class=\"menu-item\"><a href=\"#\" data-feedback-fish-userid=\"$current_user->user_email\" data-feedback-fish>Send feedback</a></li>";
+    }
+    return $items;
+}
+add_filter('wp_nav_menu_items', 'add_feedback_fish_nav_menu_item', 10, 2);
+
+// Add "Feedback Fish" settings page to the WPAdmin menu
+function create_feedback_fish_settings_page()
+{
+    $page_title = 'Feedback Fish Settings';
+    $menu_title = 'Feedback Fish';
+    $capability = 'manage_options';
+    $slug = 'feedback_fish';
+    $callback = 'feedback_fish_settings_page_content';
+
+    add_submenu_page(
+        'plugins.php',
+        $page_title,
+        $menu_title,
+        $capability,
+        $slug,
+        $callback
+    );
+}
+add_action('admin_menu', 'create_feedback_fish_settings_page');
+
+// General content for the settings page
+function feedback_fish_settings_page_content()
+{
+    ?>
+  <div class="wrap">
+    <h2>Feedback Fish</h2>
+    <form method="post" action="options.php">
+      <?php
+      settings_fields('feedback_fish');
+      do_settings_sections('feedback_fish');
+      submit_button();?>
+    </form>
+  </div>
+<?php
+}
+
+// Setup the settings page sections
+add_action('admin_init', 'setup_feedback_fish_settings_page_sections');
+add_action('admin_init', 'setup_feeback_fish_settings_fields');
+function setup_feedback_fish_settings_page_sections()
+{
+    add_settings_section(
+        'feedback_fish_general',
+        'General',
+        'feedback_fish_settings_page_section_callback',
+        'feedback_fish'
+    );
+}
+
+function setup_feeback_fish_settings_fields()
+{
+    add_settings_field(
+        'feedback_fish_project_id',
+        'Project ID',
+        'feedback_fish_project_id_field',
+        'feedback_fish',
+        'feedback_fish_general'
+    );
+    add_settings_field(
+        'feedback_fish_manual',
+        'Manual Usage (advanced)',
+        'feedback_fish_manual_field',
+        'feedback_fish',
+        'feedback_fish_general'
+    );
+    register_setting('feedback_fish', 'feedback_fish_project_id');
+    register_setting('feedback_fish', 'feedback_fish_manual');
+}
+
+function feedback_fish_manual_field()
+{
+    echo '<label><input name="feedback_fish_manual" id="feedback_fish_manual" type="checkbox" value="1"' .
+        checked(1, get_option('feedback_fish_manual'), false) .
+        ' /> I will add the <code>data-feedback-fish</code> HTML attribute myself.</label>';
+    echo "<p class=\"description\">Enabling this stops the plugin from adding a \"Send feedback\" button to your primary navigation. See the <a href=\"https://feedback.fish/help/widget/\" target=\"_blank\">documentation</a> for more information on the HTML attribute.</p>";
+}
+
+function feedback_fish_project_id_field()
+{
+    echo '<input name="feedback_fish_project_id" id="feedback_fish_project_id" type="text" value="' .
+        get_option('feedback_fish_project_id') .
+        '" />';
+    echo '<p class="description">You can get your project ID from <a href=\"https://feedback.fish/app\" target=\"_blank\">your Feedback Fish dashboard</a>.</p>';
+}
+
+function feedback_fish_settings_page_section_callback()
+{
+}
 ?>