diff --git a/.prettierignore b/.prettierignore
index f876cbec05..fa7dad869f 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -12,14 +12,14 @@ vendor-prefixed
 /dev/data
 /mailpoet/assets/dist
 /mailpoet/assets/js/lib
-/mailpoet/assets/js/src/newsletter_editor/behaviors/tinymce_icons.js
+/mailpoet/assets/js/src/newsletter-editor/behaviors/tinymce-icons.js
 /mailpoet/generated
 /mailpoet/lang
 /mailpoet/lib/Newsletter/Renderer/Template.html
 /mailpoet/lib-3rd-party
 /mailpoet/plugin_repository
 /mailpoet/temp
-/mailpoet/tests/javascript_newsletter_editor/testBundles
+/mailpoet/tests/javascript-newsletter-editor/testBundles
 /mailpoet/tests/plugins
 /mailpoet/tools/wpscan-semgrep-rules
 /mailpoet/views
diff --git a/mailpoet/.gitignore b/mailpoet/.gitignore
index bbbfbc66f0..5e438b319d 100644
--- a/mailpoet/.gitignore
+++ b/mailpoet/.gitignore
@@ -11,7 +11,7 @@ tests/plugins
 /views/cache/**
 temp
 mailpoet.zip
-tests/javascript_newsletter_editor/testBundles
+tests/javascript-newsletter-editor/testBundles
 assets/dist
 .vagrant
 lang
@@ -27,4 +27,4 @@ tasks/phpstan/vendor
 tasks/phpstan/_phpstan-wp-source.neon
 /tools/vendor
 /storybook-static
-assets/js/src/newsletter_editor/behaviors/tinymce_icons.js
+assets/js/src/newsletter-editor/behaviors/tinymce-icons.js
diff --git a/mailpoet/RoboFile.php b/mailpoet/RoboFile.php
index 49ee8b1067..5c9d587067 100644
--- a/mailpoet/RoboFile.php
+++ b/mailpoet/RoboFile.php
@@ -360,8 +360,8 @@ class RoboFile extends \Robo\Tasks {
   public function testNewsletterEditor($xmlOutputFile = null) {
     $command = join(' ', [
       './node_modules/.bin/mocha',
-      '-r tests/javascript_newsletter_editor/mochaTestHelper.js',
-      'tests/javascript_newsletter_editor/testBundles/**/*.js',
+      '-r tests/javascript-newsletter-editor/mocha-test-helper.js',
+      'tests/javascript-newsletter-editor/testBundles/**/*.js',
       '--exit',
     ]);
 
@@ -377,7 +377,7 @@ class RoboFile extends \Robo\Tasks {
   }
 
   public function testJavascript($xmlOutputFile = null) {
-    $command = './node_modules/.bin/mocha --recursive --require tests/javascript/babel_register.js tests/javascript --extension spec.js --extension spec.ts';
+    $command = './node_modules/.bin/mocha --recursive --require tests/javascript/babel-register.js tests/javascript --extension spec.js --extension spec.ts';
 
     if (!empty($xmlOutputFile)) {
       $command .= sprintf(
diff --git a/mailpoet/assets/js/src/form-editor/form-editor.jsx b/mailpoet/assets/js/src/form-editor/form-editor.jsx
index 6da3ceb3ea..3c5beba052 100644
--- a/mailpoet/assets/js/src/form-editor/form-editor.jsx
+++ b/mailpoet/assets/js/src/form-editor/form-editor.jsx
@@ -9,7 +9,7 @@ import { initBlocks } from './blocks/blocks.jsx';
 import { initHooks } from './hooks';
 import { initTranslations } from './translations';
 import { initRichText } from './rich-text/init.ts';
-import './template_selection';
+import './template-selection';
 import { registerTranslations } from '../common';
 
 function App() {
diff --git a/mailpoet/assets/js/src/newsletter-editor/behaviors/text-editor-behavior.ts b/mailpoet/assets/js/src/newsletter-editor/behaviors/text-editor-behavior.ts
index dc0ae447d1..cc126e1087 100644
--- a/mailpoet/assets/js/src/newsletter-editor/behaviors/text-editor-behavior.ts
+++ b/mailpoet/assets/js/src/newsletter-editor/behaviors/text-editor-behavior.ts
@@ -16,7 +16,7 @@ import 'tinymce/plugins/link';
 import 'tinymce/plugins/lists';
 import 'tinymce/models/dom';
 
-import './tinymce_icons';
+import './tinymce-icons';
 
 const configurationFilter = (originalConfig: RawEditorOptions) =>
   originalConfig;
diff --git a/mailpoet/assets/js/src/newsletter-editor/webpack-index.jsx b/mailpoet/assets/js/src/newsletter-editor/webpack-index.jsx
index edb17867ef..7fc0b241ee 100644
--- a/mailpoet/assets/js/src/newsletter-editor/webpack-index.jsx
+++ b/mailpoet/assets/js/src/newsletter-editor/webpack-index.jsx
@@ -9,51 +9,51 @@ import 'sticky-kit'; // side effect - extends jQuery
 import 'velocity-animate'; // side effect - assigns to window
 
 // app
-import 'newsletter_editor/initializer.jsx'; // side effect - calls Hooks.addAction()
-import 'newsletter_editor/App'; // side effect - assigns to window
+import 'newsletter-editor/initializer.jsx'; // side effect - calls Hooks.addAction()
+import 'newsletter-editor/app'; // side effect - assigns to window
 
 // components
-import 'newsletter_editor/components/config.jsx'; // side effect - calls App.on()
-import 'newsletter_editor/components/styles.js'; // side effect - calls App.on()
-import 'newsletter_editor/components/sidebar.tsx'; // side effect - calls App.on()
-import 'newsletter_editor/components/content.js'; // side effect - calls App.on()
-import 'newsletter_editor/components/heading.js'; // side effect - calls App.on()
-import 'newsletter_editor/components/history.js'; // side effect - calls App.on()
-import 'newsletter_editor/components/save.js'; // side effect - calls App.on()
-import 'newsletter_editor/components/communication.js'; // side effect - calls App.on()
+import 'newsletter-editor/components/config.jsx'; // side effect - calls App.on()
+import 'newsletter-editor/components/styles.js'; // side effect - calls App.on()
+import 'newsletter-editor/components/sidebar.tsx'; // side effect - calls App.on()
+import 'newsletter-editor/components/content.js'; // side effect - calls App.on()
+import 'newsletter-editor/components/heading.js'; // side effect - calls App.on()
+import 'newsletter-editor/components/history.js'; // side effect - calls App.on()
+import 'newsletter-editor/components/save.js'; // side effect - calls App.on()
+import 'newsletter-editor/components/communication.js'; // side effect - calls App.on()
 
 // behaviors
-import 'newsletter_editor/behaviors/BehaviorsLookup.js'; // side effect - assings to window and Marionette
-import 'newsletter_editor/behaviors/ColorPickerBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/ContainerDropZoneBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/DraggableBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/HighlightEditingBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/MediaManagerBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/ResizableBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/SortableBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/ShowSettingsBehavior.js'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/TextEditorBehavior'; // side effect - assigns to BehaviorsLookup
-import 'newsletter_editor/behaviors/WooCommerceStylesBehavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/behaviors-lookup.js'; // side effect - assings to window and Marionette
+import 'newsletter-editor/behaviors/color-picker-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/container-drop-zone-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/draggable-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/highlight-editing-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/media-manager-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/resizable-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/sortable-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/show-settings-behavior.js'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/text-editor-behavior'; // side effect - assigns to BehaviorsLookup
+import 'newsletter-editor/behaviors/woo-commerce-styles-behavior.js'; // side effect - assigns to BehaviorsLookup
 
 // blocks
-import 'newsletter_editor/blocks/container.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/button.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/image.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/divider.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/text.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/spacer.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/footer.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/header.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/automatedLatestContent.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/automatedLatestContentLayout.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/posts.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/products.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/abandonedCartContent.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/social.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/woocommerceContent.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/woocommerceHeading.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/unknownBlockFallback.js'; // side effect - calls App.on()
-import 'newsletter_editor/blocks/coupon'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/container.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/button.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/image.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/divider.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/text.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/spacer.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/footer.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/header.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/automated-latest-content.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/automated-latest-content-layout.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/posts.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/products.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/abandoned-cart-content.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/social.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/woocommerce-content.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/woocommerce-heading.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/unknown-block-fallback.js'; // side effect - calls App.on()
+import 'newsletter-editor/blocks/coupon'; // side effect - calls App.on()
 
 // register strings for native translation with @wordpress/i18n
 import { registerTranslations } from 'common';
diff --git a/mailpoet/assets/js/src/post-editor-block/blocks.jsx b/mailpoet/assets/js/src/post-editor-block/blocks.jsx
index 726af786bc..13770fdd5e 100644
--- a/mailpoet/assets/js/src/post-editor-block/blocks.jsx
+++ b/mailpoet/assets/js/src/post-editor-block/blocks.jsx
@@ -1 +1 @@
-import './subscription_form/form_block.jsx';
+import './subscription-form/form-block.jsx';
diff --git a/mailpoet/assets/js/src/types/index.ts b/mailpoet/assets/js/src/types/index.ts
index 7125b4cb34..55e666e3a4 100644
--- a/mailpoet/assets/js/src/types/index.ts
+++ b/mailpoet/assets/js/src/types/index.ts
@@ -27,7 +27,7 @@ import {
   useCompositeState,
 } from 'reakit/Composite';
 
-import './wordpress_modules';
+import './wordpress-modules';
 
 /* eslint-disable @typescript-eslint/no-explicit-any -- some general types in this file need to use "any"  */
 /* eslint-disable @typescript-eslint/naming-convention -- we have no control over 3rd-party naming conventions */
diff --git a/mailpoet/assets/js/src/webpack-admin-index.tsx b/mailpoet/assets/js/src/webpack-admin-index.tsx
index 5ab1ea7495..37c1005d3a 100644
--- a/mailpoet/assets/js/src/webpack-admin-index.tsx
+++ b/mailpoet/assets/js/src/webpack-admin-index.tsx
@@ -11,13 +11,13 @@ import 'segments/static/static'; // side effect - renders ReactDOM to document
 import 'segments/dynamic/dynamic'; // side effect - renders ReactDOM to document
 import 'forms/forms.jsx'; // side effect - renders ReactDOM to document
 import 'help/help.jsx'; // side effect - renders ReactDOM to document
-import 'subscribers/importExport/import.jsx'; // side effect - executes on doc ready, adds events
-import 'subscribers/importExport/export'; // side effect - executes on doc ready
+import 'subscribers/import-export/import.jsx'; // side effect - executes on doc ready, adds events
+import 'subscribers/import-export/export'; // side effect - executes on doc ready
 import 'wizard/wizard'; // side effect - renders ReactDOM to document
-import 'experimental_features/experimental_features.jsx'; // side effect - renders ReactDOM to document
+import 'experimental-features/experimental-features.jsx'; // side effect - renders ReactDOM to document
 import 'logs/logs'; // side effect - renders ReactDOM to document
 import 'sending-paused-notices-fix-button'; // side effect - renders ReactDOM to document
 import 'sending-paused-notices-resume-button'; // side effect - executes on doc ready, adds events
 import 'sending-paused-notices-authorize-email'; // side effect - renders ReactDOM to document
 import 'landingpage/landingpage'; // side effect - renders ReactDOM to document
-import 'wizard/track_wizard_loaded_via_woocommerce';
+import 'wizard/track-wizard-loaded-via-woocommerce';
diff --git a/mailpoet/assets/js/src/webpack-mailpoet-index.jsx b/mailpoet/assets/js/src/webpack-mailpoet-index.jsx
index dd8917d1e1..8902e9c907 100644
--- a/mailpoet/assets/js/src/webpack-mailpoet-index.jsx
+++ b/mailpoet/assets/js/src/webpack-mailpoet-index.jsx
@@ -6,6 +6,6 @@
 
 import 'mailpoet'; // side effect - assigns MailPoet to window
 import 'dismissible-notice.jsx'; // side effect - adds jQuery event
-import 'jquery.serialize_object'; // side effect - extends jQuery
+import 'jquery.serialize-object'; // side effect - extends jQuery
 import 'parsleyjs'; // side effect - extends jQuery
 import 'parsley-validators.jsx';
diff --git a/mailpoet/assets/js/src/webpack-public-index.jsx b/mailpoet/assets/js/src/webpack-public-index.jsx
index afdcdcefd2..1500b2b012 100644
--- a/mailpoet/assets/js/src/webpack-public-index.jsx
+++ b/mailpoet/assets/js/src/webpack-public-index.jsx
@@ -5,5 +5,5 @@
 // Code can be gradually refactored to avoid side effects completely.
 
 import 'mailpoet'; // side effect - assigns MailPoet to window
-import 'jquery.serialize_object'; // side effect - extends jQuery
+import 'jquery.serialize-object'; // side effect - extends jQuery
 import 'public.tsx'; // side effect - assigns to window, sets up form validation, etc.
diff --git a/mailpoet/assets/js/src/webpack-vendor-index.jsx b/mailpoet/assets/js/src/webpack-vendor-index.jsx
index ae3175354a..390e05e9a2 100644
--- a/mailpoet/assets/js/src/webpack-vendor-index.jsx
+++ b/mailpoet/assets/js/src/webpack-vendor-index.jsx
@@ -5,5 +5,5 @@
 // Code can be gradually refactored to avoid side effects completely.
 
 import 'handlebars'; // no side effect - this just explicitly requires Handlebars
-import 'handlebars_helpers'; // side effect - extends Handlebars, assigns to window
+import 'handlebars-helpers'; // side effect - extends Handlebars, assigns to window
 import 'wp-js-hooks'; // side effect - assigns to window
diff --git a/mailpoet/eslint.config.js b/mailpoet/eslint.config.js
index bc642229f6..46ad31c918 100644
--- a/mailpoet/eslint.config.js
+++ b/mailpoet/eslint.config.js
@@ -7,14 +7,14 @@ module.exports = [
   {
     ignores: [
       'assets/js/src/vendor/**',
-      'tests/javascript_newsletter_editor/testBundles/**',
+      'tests/javascript-newsletter-editor/testBundles/**',
     ],
   },
   ...es5Config.map((config) => ({
     ...config,
     files: [
       'assets/js/src/**/*.js',
-      'tests/javascript_newsletter_editor/**/*.js',
+      'tests/javascript-newsletter-editor/**/*.js',
     ],
   })),
   ...es6Config.map((config) => ({
@@ -28,7 +28,7 @@ module.exports = [
 
   // ES5 config overrides
   {
-    files: ['tests/javascript_newsletter_editor/**/*.js'],
+    files: ['tests/javascript-newsletter-editor/**/*.js'],
     languageOptions: {
       globals: {
         ...globals.mocha,
@@ -75,11 +75,11 @@ module.exports = [
   // (These are existing violations that we should fix at some point.)
   {
     files: [
-      'assets/js/src/common/premium_key/key_activation_button.tsx',
+      'assets/js/src/common/premium-key/key-activation-button.tsx',
       'assets/js/src/settings/pages/advanced/reinstall.tsx',
-      'assets/js/src/settings/pages/advanced/recalculate_subscriber_score.tsx',
-      'assets/js/src/settings/pages/send_with/other/activate_or_cancel.tsx',
-      'assets/js/src/settings/pages/send_with/send_with_choice.tsx',
+      'assets/js/src/settings/pages/advanced/recalculate-subscriber-score.tsx',
+      'assets/js/src/settings/pages/send-with/other/activate-or-cancel.tsx',
+      'assets/js/src/settings/pages/send-with/send-with-choice.tsx',
     ],
     rules: {
       '@typescript-eslint/await-thenable': 0,
@@ -87,14 +87,14 @@ module.exports = [
   },
   {
     files: [
-      'assets/js/src/common/tabs/routed_tabs.tsx',
+      'assets/js/src/common/tabs/routed-tabs.tsx',
       'assets/js/src/common/thumbnail.ts',
-      'assets/js/src/form_editor/components/form_settings/form_placement_options/settings_panels/placement_settings.tsx',
-      'assets/js/src/form_editor/form_preview.ts',
-      'assets/js/src/newsletters/campaign_stats/newsletter_general_stats.tsx',
+      'assets/js/src/form-editor/components/form-settings/form-placement-options/settings-panels/placement-settings.tsx',
+      'assets/js/src/form-editor/form-preview.ts',
+      'assets/js/src/newsletters/campaign-stats/newsletter-general-stats.tsx',
       'assets/js/src/newsletters/types.tsx',
-      'assets/js/src/settings/store/normalize_settings.ts',
-      'assets/js/src/subscribers/importExport/export.ts',
+      'assets/js/src/settings/store/normalize-settings.ts',
+      'assets/js/src/subscribers/import-export/export.ts',
     ],
     rules: {
       '@typescript-eslint/restrict-template-expressions': 0,
@@ -106,64 +106,64 @@ module.exports = [
       'assets/js/src/automation/editor/components/automation/index.tsx',
       'assets/js/src/automation/editor/components/automation/separator.tsx',
       'assets/js/src/automation/editor/components/header/index.tsx',
-      'assets/js/src/automation/editor/components/header/inserter_toggle.tsx',
+      'assets/js/src/automation/editor/components/header/inserter-toggle.tsx',
       'assets/js/src/automation/editor/components/sidebar/header.tsx',
       'assets/js/src/automation/editor/index.tsx',
       'assets/js/src/automation/editor/store/actions.ts',
       'assets/js/src/automation/integrations/core/steps/delay/edit.tsx',
-      'assets/js/src/automation/integrations/mailpoet/steps/send_email/edit/edit_newsletter.tsx',
-      'assets/js/src/automation/integrations/mailpoet/steps/send_email/edit/email_panel.tsx',
-      'assets/js/src/automation/integrations/mailpoet/steps/send_email/edit/reply_to_panel.tsx',
-      'assets/js/src/automation/integrations/mailpoet/steps/send_email/index.tsx',
+      'assets/js/src/automation/integrations/mailpoet/steps/send-email/edit/edit-newsletter.tsx',
+      'assets/js/src/automation/integrations/mailpoet/steps/send-email/edit/email-panel.tsx',
+      'assets/js/src/automation/integrations/mailpoet/steps/send-email/edit/reply-to-panel.tsx',
+      'assets/js/src/automation/integrations/mailpoet/steps/send-email/index.tsx',
       'assets/js/src/automation/listing/store/reducer.ts',
-      'assets/js/src/common/error_boundary/utils.ts',
-      'assets/js/src/common/functions/parsley_helper_functions.ts',
-      'assets/js/src/common/listings/newsletter_stats/stats.tsx',
-      'assets/js/src/common/top_bar/mailpoet_logo_responsive.tsx',
+      'assets/js/src/common/error-boundary/utils.ts',
+      'assets/js/src/common/functions/parsley-helper-functions.ts',
+      'assets/js/src/common/listings/newsletter-stats/stats.tsx',
+      'assets/js/src/common/top-bar/mailpoet-logo-responsive.tsx',
       'assets/js/src/date.ts',
-      'assets/js/src/form/fields/tokenField.tsx',
-      'assets/js/src/form_editor/components/form_settings/form_placement_options/settings_panels/placement_settings.tsx',
-      'assets/js/src/form_editor/form_preview.ts',
-      'assets/js/src/form_editor/store/blocks_to_form_body.ts',
-      'assets/js/src/form_editor/store/controls.tsx',
-      'assets/js/src/form_editor/store/reducers/change_active_sidebar.ts',
-      'assets/js/src/form_editor/store/reducers/toggle_form.ts',
-      'assets/js/src/form_editor/store/reducers/toggle_fullscreen.ts',
-      'assets/js/src/form_editor/store/reducers/toggle_sidebar.ts',
-      'assets/js/src/form_editor/store/reducers/tutorial_dismiss.ts',
-      'assets/js/src/form_editor/store/selectors.ts',
+      'assets/js/src/form/fields/token-field.tsx',
+      'assets/js/src/form-editor/components/form-settings/form-placement-options/settings-panels/placement-settings.tsx',
+      'assets/js/src/form-editor/form-preview.ts',
+      'assets/js/src/form-editor/store/blocks-to-form-body.ts',
+      'assets/js/src/form-editor/store/controls.tsx',
+      'assets/js/src/form-editor/store/reducers/change-active-sidebar.ts',
+      'assets/js/src/form-editor/store/reducers/toggle-form.ts',
+      'assets/js/src/form-editor/store/reducers/toggle-fullscreen.ts',
+      'assets/js/src/form-editor/store/reducers/toggle-sidebar.ts',
+      'assets/js/src/form-editor/store/reducers/tutorial-dismiss.ts',
+      'assets/js/src/form-editor/store/selectors.ts',
       'assets/js/src/homepage/components/product-discovery.tsx',
       'assets/js/src/homepage/components/task-list.tsx',
-      'assets/js/src/marketing_optin_block/frontend.ts',
-      'assets/js/src/newsletter_editor/behaviors/TextEditorBehavior.ts',
-      'assets/js/src/newsletter_editor/blocks/coupon.tsx',
-      'assets/js/src/newsletter_editor/blocks/coupon/settings_header.tsx',
-      'assets/js/src/newsletters/automatic_emails/events/event_options.tsx',
-      'assets/js/src/newsletters/listings/heading_steps.tsx',
+      'assets/js/src/marketing-optin-block/frontend.ts',
+      'assets/js/src/newsletter-editor/behaviors/text-editor-behavior.ts',
+      'assets/js/src/newsletter-editor/blocks/coupon.tsx',
+      'assets/js/src/newsletter-editor/blocks/coupon/settings-header.tsx',
+      'assets/js/src/newsletters/automatic-emails/events/event-options.tsx',
+      'assets/js/src/newsletters/listings/heading-steps.tsx',
       'assets/js/src/newsletters/send.tsx',
-      'assets/js/src/newsletters/send/congratulate/success_pitch_mss.tsx',
-      'assets/js/src/newsletters/send/ga_tracking.tsx',
-      'assets/js/src/newsletters/send/re_engagement.tsx',
+      'assets/js/src/newsletters/send/congratulate/success-pitch-mss.tsx',
+      'assets/js/src/newsletters/send/ga-tracking.tsx',
+      'assets/js/src/newsletters/send/re-engagement.tsx',
       'assets/js/src/newsletters/send/standard.tsx',
       'assets/js/src/newsletters/types.tsx',
-      'assets/js/src/notices/email_volume_limit_notice.tsx',
-      'assets/js/src/segments/dynamic/dynamic_segments_filters/fields/subscriber/subscriber_tag.tsx',
-      'assets/js/src/segments/dynamic/dynamic_segments_filters/woocommerce.tsx',
-      'assets/js/src/segments/dynamic/subscribers_counter.tsx',
+      'assets/js/src/notices/email-volume-limit-notice.tsx',
+      'assets/js/src/segments/dynamic/dynamic-segments-filters/fields/subscriber/subscriber-tag.tsx',
+      'assets/js/src/segments/dynamic/dynamic-segments-filters/woocommerce.tsx',
+      'assets/js/src/segments/dynamic/subscribers-counter.tsx',
       'assets/js/src/segments/dynamic/validator.ts',
       'assets/js/src/sending-paused-notices-resume-button.ts',
-      'assets/js/src/settings/pages/basics/stats_notifications.tsx',
-      'assets/js/src/settings/pages/basics/subscribe_on.tsx',
-      'assets/js/src/settings/pages/signup_confirmation/confirmation_email_customizer.tsx',
-      'assets/js/src/settings/pages/woo_commerce/checkout_optin.tsx',
-      'assets/js/src/settings/pages/woo_commerce/email_customizer.tsx',
-      'assets/js/src/settings/pages/woo_commerce/subscribe_old_customers.tsx',
+      'assets/js/src/settings/pages/basics/stats-notifications.tsx',
+      'assets/js/src/settings/pages/basics/subscribe-on.tsx',
+      'assets/js/src/settings/pages/signup-confirmation/confirmation-email-customizer.tsx',
+      'assets/js/src/settings/pages/woo-commerce/checkout-optin.tsx',
+      'assets/js/src/settings/pages/woo-commerce/email-customizer.tsx',
+      'assets/js/src/settings/pages/woo-commerce/subscribe-old-customers.tsx',
       'assets/js/src/settings/store/actions/settings.ts',
-      'assets/js/src/settings/store/hooks/useSelector.ts',
-      'assets/js/src/settings/store/hooks/useSetting.ts',
-      'assets/js/src/settings/store/normalize_settings.ts',
-      'assets/js/src/subscribers/importExport/export.ts',
-      'assets/js/src/wizard/welcome_wizard_controller.tsx',
+      'assets/js/src/settings/store/hooks/use-selector.ts',
+      'assets/js/src/settings/store/hooks/use-setting.ts',
+      'assets/js/src/settings/store/normalize-settings.ts',
+      'assets/js/src/subscribers/import-export/export.ts',
+      'assets/js/src/wizard/welcome-wizard-controller.tsx',
     ],
     rules: {
       '@typescript-eslint/no-unsafe-return': 0,
diff --git a/mailpoet/lib/EmailEditor/Integrations/MailPoet/EmailEditor.php b/mailpoet/lib/EmailEditor/Integrations/MailPoet/EmailEditor.php
index 4a04d33ea1..b53e3c3dd5 100644
--- a/mailpoet/lib/EmailEditor/Integrations/MailPoet/EmailEditor.php
+++ b/mailpoet/lib/EmailEditor/Integrations/MailPoet/EmailEditor.php
@@ -95,10 +95,10 @@ class EmailEditor {
     if (!$screen || self::MAILPOET_EMAIL_POST_TYPE !== $screen->post_type) { // phpcs:ignore Squiz.NamingConventions.ValidVariableName.MemberNotCamelCaps
       return;
     }
-    $assetsParams = require_once Env::$assetsPath . '/dist/js/email_editor/email_editor.asset.php';
+    $assetsParams = require_once Env::$assetsPath . '/dist/js/email-editor/email_editor.asset.php';
     $this->wp->wpEnqueueScript(
       'mailpoet_email_editor',
-      Env::$assetsUrl . '/dist/js/email_editor/email_editor.js',
+      Env::$assetsUrl . '/dist/js/email-editor/email_editor.js',
       $assetsParams['dependencies'],
       $assetsParams['version'],
       true
@@ -106,7 +106,7 @@ class EmailEditor {
 
     $this->wp->wpEnqueueStyle(
       'mailpoet_email_editor',
-      Env::$assetsUrl . '/dist/js/email_editor/email_editor.css',
+      Env::$assetsUrl . '/dist/js/email-editor/email_editor.css',
       [],
       $assetsParams['version']
     );
diff --git a/mailpoet/lib/PostEditorBlocks/MarketingOptinBlock.php b/mailpoet/lib/PostEditorBlocks/MarketingOptinBlock.php
index 3c973d96bd..9da3071f4b 100644
--- a/mailpoet/lib/PostEditorBlocks/MarketingOptinBlock.php
+++ b/mailpoet/lib/PostEditorBlocks/MarketingOptinBlock.php
@@ -34,7 +34,7 @@ class MarketingOptinBlock implements IntegrationInterface {
    * Register block scripts and assets.
    */
   public function initialize() {
-    $script_asset_path = Env::$assetsPath . '/dist/js/marketing_optin_block/marketing-optin-block-frontend.asset.php';
+    $script_asset_path = Env::$assetsPath . '/dist/js/marketing-optin-block/marketing-optin-block-frontend.asset.php';
     $script_asset = file_exists($script_asset_path)
       ? require $script_asset_path
       : [
@@ -43,7 +43,7 @@ class MarketingOptinBlock implements IntegrationInterface {
       ];
     $this->wp->wpRegisterScript(
       'mailpoet-marketing-optin-block-frontend',
-      Env::$assetsUrl . '/dist/js/marketing_optin_block/marketing-optin-block-frontend.js',
+      Env::$assetsUrl . '/dist/js/marketing-optin-block/marketing-optin-block-frontend.js',
       $script_asset['dependencies'],
       $script_asset['version'],
       true
diff --git a/mailpoet/lib/PostEditorBlocks/WooCommerceBlocksIntegration.php b/mailpoet/lib/PostEditorBlocks/WooCommerceBlocksIntegration.php
index 662d036df2..60595e13b9 100644
--- a/mailpoet/lib/PostEditorBlocks/WooCommerceBlocksIntegration.php
+++ b/mailpoet/lib/PostEditorBlocks/WooCommerceBlocksIntegration.php
@@ -77,7 +77,7 @@ class WooCommerceBlocksIntegration {
       '__experimental_woocommerce_blocks_add_data_attributes_to_block',
       [$this, 'addDataAttributesToBlock']
     );
-    $block = $this->wp->registerBlockTypeFromMetadata(Env::$assetsPath . '/dist/js/marketing_optin_block');
+    $block = $this->wp->registerBlockTypeFromMetadata(Env::$assetsPath . '/dist/js/marketing-optin-block');
     // We need to force the script to load in the footer. register_block_type always adds the script to the header.
     if ($block instanceof \WP_Block_Type && $block->editor_script) { // phpcs:ignore Squiz.NamingConventions.ValidVariableName.MemberNotCamelCaps
       $wpScripts = $this->wp->getWpScripts();
diff --git a/mailpoet/package.json b/mailpoet/package.json
index 1af3ef7773..f62997789b 100644
--- a/mailpoet/package.json
+++ b/mailpoet/package.json
@@ -4,12 +4,12 @@
     "extends @wordpress/browserslist-config"
   ],
   "scripts": {
-    "lint": "NODE_OPTIONS=--max_old_space_size=2048 eslint --max-warnings 0 'assets/js/src/**/*.{js,jsx,ts,tsx}' 'tests/javascript_newsletter_editor/**/*.js'",
+    "lint": "NODE_OPTIONS=--max_old_space_size=2048 eslint --max-warnings 0 'assets/js/src/**/*.{js,jsx,ts,tsx}' 'tests/javascript-newsletter-editor/**/*.js'",
     "autoprefixer": "postcss assets/dist/css/*.css --use autoprefixer --no-map --replace",
     "scss": "sass assets/css/src/:assets/dist/css/ --style compressed",
     "stylelint": "stylelint --fix",
     "stylelint-check": "stylelint",
-    "test": "env NODE_PATH=$NODE_PATH:./assets/js/src mocha --recursive --require tests/javascript/babel_register.js  tests/javascript --extension spec.js --extension spec.ts",
+    "test": "env NODE_PATH=$NODE_PATH:./assets/js/src mocha --recursive --require tests/javascript/babel-register.js  tests/javascript --extension spec.js --extension spec.ts",
     "check-types": "tsc --noEmit",
     "storybook": "start-storybook -s ./ -p 8083",
     "build-storybook": "build-storybook",
diff --git a/mailpoet/tasks/npm_post_install.sh b/mailpoet/tasks/npm_post_install.sh
index 21abdb34be..67757c3fd3 100755
--- a/mailpoet/tasks/npm_post_install.sh
+++ b/mailpoet/tasks/npm_post_install.sh
@@ -1,12 +1,12 @@
 #!/bin/bash
 
 echo "/* eslint-disable */
-" > $INIT_CWD/assets/js/src/newsletter_editor/behaviors/tinymce-icons.js
+" > $INIT_CWD/assets/js/src/newsletter-editor/behaviors/tinymce-icons.js
 
 echo "import tinymce from 'tinymce/tinymce';
-" >> $INIT_CWD/assets/js/src/newsletter_editor/behaviors/tinymce-icons.js
+" >> $INIT_CWD/assets/js/src/newsletter-editor/behaviors/tinymce-icons.js
 
-cat $INIT_CWD/node_modules/tinymce/icons/default/icons.min.js >> $INIT_CWD/assets/js/src/newsletter_editor/behaviors/tinymce-icons.js
+cat $INIT_CWD/node_modules/tinymce/icons/default/icons.min.js >> $INIT_CWD/assets/js/src/newsletter-editor/behaviors/tinymce-icons.js
 
 # fix SCSS file being exposed as CSS file so it can be imported correctly
 cp $INIT_CWD/node_modules/react-dates/lib/css/_datepicker.css $INIT_CWD/node_modules/react-dates/lib/css/_datepicker.scss
diff --git a/mailpoet/tests/javascript-newsletter-editor/mocha-test-helper.js b/mailpoet/tests/javascript-newsletter-editor/mocha-test-helper.js
index ed7dbbc5ce..a79a0c7990 100644
--- a/mailpoet/tests/javascript-newsletter-editor/mocha-test-helper.js
+++ b/mailpoet/tests/javascript-newsletter-editor/mocha-test-helper.js
@@ -43,7 +43,7 @@ global.window.wp = global.window.wp || {
 };
 
 testHelpers.loadScript(
-  'tests/javascript_newsletter_editor/testBundles/vendor.js',
+  'tests/javascript-newsletter-editor/testBundles/vendor.js',
   global.window,
 );
 const Handlebars = global.window.Handlebars;
diff --git a/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/blocks/automated-latest-content-layout.spec.js b/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/blocks/automated-latest-content-layout.spec.js
index 7e6ab86ea1..7bbc28fc20 100644
--- a/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/blocks/automated-latest-content-layout.spec.js
+++ b/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/blocks/automated-latest-content-layout.spec.js
@@ -35,7 +35,7 @@ describe('Automated Latest Content Layout Supervisor', function () {
       .returns(jQuery.Deferred());
 
     module = AutomatedLatestContentInjector({
-      'newsletter_editor/components/communication': {
+      'newsletter-editor/components/communication': {
         CommunicationComponent: {
           getBulkTransformedPosts: mock,
         },
@@ -410,7 +410,7 @@ describe('Automated latest content layout', function () {
 
     before(function () {
       module = AutomatedLatestContentInjector({
-        'newsletter_editor/components/communication': {
+        'newsletter-editor/components/communication': {
           CommunicationComponent: {
             getPostTypes: function () {
               return jQuery.Deferred();
diff --git a/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/components/save.spec.js b/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/components/save.spec.js
index 3e9ffdadc3..0426e7e557 100644
--- a/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/components/save.spec.js
+++ b/mailpoet/tests/javascript-newsletter-editor/newsletter-editor/components/save.spec.js
@@ -15,7 +15,7 @@ describe('Save', function () {
     var module;
     before(function () {
       module = SaveInjector({
-        'newsletter_editor/components/communication': {
+        'newsletter-editor/components/communication': {
           CommunicationComponent: {
             saveNewsletter: function () {
               return jQuery.Deferred();
@@ -53,7 +53,7 @@ describe('Save', function () {
         },
       });
       innerModule = SaveInjector({
-        'newsletter_editor/components/communication': {
+        'newsletter-editor/components/communication': {
           CommunicationComponent: {
             saveNewsletter: sinon.stub().returns(promise),
           },
@@ -67,7 +67,7 @@ describe('Save', function () {
     it('sends newsletter json to server for saving', function () {
       var mock = sinon.mock().once().returns(jQuery.Deferred());
       var innerModule = SaveInjector({
-        'newsletter_editor/components/communication': {
+        'newsletter-editor/components/communication': {
           CommunicationComponent: {
             saveNewsletter: mock,
           },
@@ -97,7 +97,7 @@ describe('Save', function () {
         body: body,
       });
       innerModule = SaveInjector({
-        'newsletter_editor/components/communication': {
+        'newsletter-editor/components/communication': {
           CommunicationComponent: {
             saveNewsletter: mock,
           },
@@ -277,7 +277,7 @@ describe('Save', function () {
               trackEvent: function () {},
             },
           },
-          'newsletter_editor/App': { App },
+          'newsletter-editor/app': { App },
           common: {
             fromNewsletter: function () {
               return promiseMock;
@@ -309,7 +309,7 @@ describe('Save', function () {
       it('saves newsletter when clicked on "next" button', function () {
         var spy = sinon.spy();
         var module = SaveInjector({
-          'newsletter_editor/components/communication': {
+          'newsletter-editor/components/communication': {
             CommunicationComponent: {
               saveNewsletter: function () {
                 return jQuery.Deferred();
diff --git a/mailpoet/tsconfig.json b/mailpoet/tsconfig.json
index 6537b5517c..2ba5bb62cd 100644
--- a/mailpoet/tsconfig.json
+++ b/mailpoet/tsconfig.json
@@ -4,7 +4,7 @@
     "assets/js/src/**/*",
     "assets/js/src/**/*.json",
     "tests/javascript/**/*.ts",
-    "tests/javascript_newsletter_editor/**/*.ts"
+    "tests/javascript-newsletter-editor/**/*.ts"
   ],
   "compilerOptions": {
     "baseUrl": "./assets/js/src",
diff --git a/mailpoet/webpack.config.js b/mailpoet/webpack.config.js
index 1311841b0d..4cf6f2e6d7 100644
--- a/mailpoet/webpack.config.js
+++ b/mailpoet/webpack.config.js
@@ -122,7 +122,7 @@ const baseConfig = {
       {
         include: path.resolve(
           __dirname,
-          'assets/js/src/webpack_admin_expose.js',
+          'assets/js/src/webpack-admin-expose.js',
         ),
         loader: 'expose-loader',
         options: { exposes: globalPrefix },
@@ -195,17 +195,17 @@ const baseConfig = {
 const adminConfig = {
   name: 'admin',
   entry: {
-    vendor: 'webpack_vendor_index.jsx',
-    mailpoet: 'webpack_mailpoet_index.jsx',
-    admin_vendor: ['prop-types', 'lodash', 'webpack_admin_expose.js'], // libraries shared between free and premium plugin
-    admin: 'webpack_admin_index.tsx',
+    vendor: 'webpack-vendor-index.jsx',
+    mailpoet: 'webpack-mailpoet-index.jsx',
+    admin_vendor: ['prop-types', 'lodash', 'webpack-admin-expose.js'], // libraries shared between free and premium plugin
+    admin: 'webpack-admin-index.tsx',
     automation: 'automation/automation.tsx',
     automation_editor: 'automation/editor/index.tsx',
     automation_analytics:
       'automation/integrations/mailpoet/analytics/index.tsx',
     automation_templates: 'automation/templates/index.tsx',
-    newsletter_editor: 'newsletter_editor/webpack_index.jsx',
-    form_editor: 'form_editor/form_editor.jsx',
+    newsletter_editor: 'newsletter-editor/webpack-index.jsx',
+    form_editor: 'form-editor/form-editor.jsx',
     settings: 'settings/index.tsx',
   },
   plugins: [
@@ -241,7 +241,7 @@ const adminConfig = {
 const publicConfig = {
   name: 'public',
   entry: {
-    public: 'webpack_public_index.jsx',
+    public: 'webpack-public-index.jsx',
   },
   plugins: [
     ...baseConfig.plugins,
@@ -249,7 +249,7 @@ const publicConfig = {
     // replace MailPoet definition with a smaller version for public
     new webpack.NormalModuleReplacementPlugin(
       /mailpoet\.ts/,
-      './mailpoet_public.ts',
+      './mailpoet-public.ts',
     ),
   ],
   externals: {
@@ -261,10 +261,10 @@ const publicConfig = {
 const testConfig = {
   name: 'test',
   entry: {
-    vendor: 'webpack_vendor_index.jsx',
+    vendor: 'webpack-vendor-index.jsx',
     testNewsletterEditor: [
-      'webpack_mailpoet_index.jsx',
-      'newsletter_editor/webpack_index.jsx',
+      'webpack-mailpoet-index.jsx',
+      'newsletter-editor/webpack-index.jsx',
 
       'components/config.spec.js',
       'components/content.spec.js',
@@ -275,7 +275,7 @@ const testConfig = {
       'components/styles.spec.js',
       'components/communication.spec.js',
 
-      'blocks/automatedLatestContentLayout.spec.js',
+      'blocks/automated-latest-content-layout.spec.js',
       'blocks/button.spec.js',
       'blocks/container.spec.js',
       'blocks/coupon.spec.js',
@@ -293,7 +293,7 @@ const testConfig = {
   output: {
     path: path.join(
       __dirname,
-      'tests/javascript_newsletter_editor/testBundles',
+      'tests/javascript-newsletter-editor/testBundles',
     ),
     filename: '[name].js',
   },
@@ -301,14 +301,14 @@ const testConfig = {
     // replace MailPoet definition with a smaller version for public
     new webpack.NormalModuleReplacementPlugin(
       /mailpoet\.js/,
-      './mailpoet_tests.js',
+      './mailpoet-tests.js',
     ),
   ],
   resolve: {
     modules: [
       'node_modules',
       'assets/js/src',
-      'tests/javascript_newsletter_editor/newsletter_editor',
+      'tests/javascript-newsletter-editor/newsletter-editor',
     ],
     extensions: ['.js', '.jsx', '.ts', '.tsx'],
     alias: {
@@ -335,7 +335,7 @@ const testConfig = {
 const formPreviewConfig = {
   name: 'form_preview',
   entry: {
-    form_preview: 'form_editor/form_preview.ts',
+    form_preview: 'form-editor/form-preview.ts',
   },
   externals: {
     jquery: 'jQuery',
@@ -346,7 +346,7 @@ const formPreviewConfig = {
 const postEditorBlock = {
   name: 'post_editor_block',
   entry: {
-    post_editor_block: 'post_editor_block/blocks.jsx',
+    post_editor_block: 'post-editor-block/blocks.jsx',
   },
 };
 
@@ -384,13 +384,13 @@ const marketingOptinBlock = Object.assign({}, wpScriptConfig, {
   stats,
   name: 'marketing_optin_block',
   entry: {
-    'marketing-optin-block': '/assets/js/src/marketing_optin_block/index.tsx',
+    'marketing-optin-block': '/assets/js/src/marketing-optin-block/index.tsx',
     'marketing-optin-block-frontend':
-      '/assets/js/src/marketing_optin_block/frontend.ts',
+      '/assets/js/src/marketing-optin-block/frontend.ts',
   },
   output: {
     filename: '[name].js',
-    path: path.join(__dirname, 'assets/dist/js/marketing_optin_block'),
+    path: path.join(__dirname, 'assets/dist/js/marketing-optin-block'),
   },
   module: Object.assign({}, wpScriptConfig.module, {
     rules: [
@@ -431,7 +431,7 @@ const marketingOptinBlock = Object.assign({}, wpScriptConfig, {
     new WebpackCopyPlugin({
       patterns: [
         {
-          from: 'assets/js/src/marketing_optin_block/block.json',
+          from: 'assets/js/src/marketing-optin-block/block.json',
           to: 'block.json',
         },
       ],
@@ -442,11 +442,11 @@ const marketingOptinBlock = Object.assign({}, wpScriptConfig, {
 const emailEditor = Object.assign({}, wpScriptConfig, {
   name: 'email_editor',
   entry: {
-    email_editor: 'email_editor/index.ts',
+    email_editor: 'email-editor/index.ts',
   },
   output: {
     filename: '[name].js',
-    path: path.join(__dirname, 'assets/dist/js/email_editor'),
+    path: path.join(__dirname, 'assets/dist/js/email-editor'),
   },
   resolve: {
     ...wpScriptConfig.resolve,