diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 52c2af7..51cc44d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -27,104 +27,156 @@ Compatibility reports are always helpful. They're tracked in a separate reposito
 Either fork and edit the messages files manually or to easily add/edit localizations, use the web-ext-translator tool:
 https://lusito.github.io/web-ext-translator/?gh=https://github.com/hensm/fx_cast/
 
-Missing/outdated strings:
+<details>
+    <summary>Missing/outdated strings:</summary>
 
--   `de`
+- `de`
 
-    -   `optionsMirroringCategoryName`
-    -   `optionsMirroringCategoryDescription`
-    -   `optionsMirroringEnabled`
-    -   `optionsMirroringAppId`
-    -   `optionsBridgeCompatible`
-    -   `optionsBridgeLikelyCompatible`
-    -   `optionsBridgeIncompatible`
-    -   `optionsSiteWhitelistCategoryName`
-    -   `optionsSiteWhitelistCategoryDescription`
-    -   `optionsSiteWhitelistEnabled`
-    -   `optionsSiteWhitelistEnabledDescription`
-    -   `optionsSiteWhitelistContent`
-    -   `optionsSiteWhitelistBasicView`
-    -   `optionsSiteWhitelistRawView`
-    -   `optionsSiteWhitelistSaveRaw`
-    -   `optionsSiteWhitelistAddItem`
-    -   `optionsSiteWhitelistUserAgent`
-    -   `optionsSiteWhitelistEditItem`
-    -   `optionsSiteWhitelistRemoveItem`
-    -   `optionsSiteWhitelistInvalidMatchPattern`
-    -   `popupWhitelistNotWhitelisted`
-    -   `popupWhitelistAddToWhitelist`
-    -   `popupMediaTypeAppNotFound`
-    -   `popupCastMenuTitle`
-    -   `popupStopMenuTitle`
+    - `optionsMirroringCategoryName`
+    - `optionsMirroringCategoryDescription`
+    - `optionsMirroringEnabled`
+    - `optionsMirroringAppId`
+    - `optionsBridgeCompatible`
+    - `optionsBridgeLikelyCompatible`
+    - `optionsBridgeIncompatible`
+    - `optionsSiteWhitelistCategoryName`
+    - `optionsSiteWhitelistCategoryDescription`
+    - `optionsSiteWhitelistEnabled`
+    - `optionsSiteWhitelistEnabledDescription`
+    - `optionsSiteWhitelistContent`
+    - `optionsSiteWhitelistBasicView`
+    - `optionsSiteWhitelistRawView`
+    - `optionsSiteWhitelistSaveRaw`
+    - `optionsSiteWhitelistAddItem`
+    - `optionsSiteWhitelistUserAgent`
+    - `optionsSiteWhitelistEditItem`
+    - `optionsSiteWhitelistRemoveItem`
+    - `optionsSiteWhitelistInvalidMatchPattern`
+    - `popupWhitelistNotWhitelisted`
+    - `popupWhitelistAddToWhitelist`
+    - `popupMediaTypeAppNotFound`
+    - `popupCastMenuTitle`
+    - `popupStopMenuTitle`
 
--   `es`
+- `es`
 
-    -   `optionsSiteWhitelistCategoryName`
-    -   `optionsSiteWhitelistCategoryDescription`
-    -   `optionsSiteWhitelistEnabled`
-    -   `optionsSiteWhitelistEnabledDescription`
-    -   `optionsSiteWhitelistContent`
-    -   `optionsSiteWhitelistBasicView`
-    -   `optionsSiteWhitelistRawView`
-    -   `optionsSiteWhitelistSaveRaw`
-    -   `optionsSiteWhitelistAddItem`
-    -   `optionsSiteWhitelistUserAgent`
-    -   `optionsSiteWhitelistEditItem`
-    -   `optionsSiteWhitelistRemoveItem`
-    -   `optionsSiteWhitelistInvalidMatchPattern`
-    -   `popupWhitelistNotWhitelisted`
-    -   `popupWhitelistAddToWhitelist`
-    -   `popupCastMenuTitle`
-    -   `popupStopMenuTitle`
+    - `optionsSiteWhitelistCategoryName`
+    - `optionsSiteWhitelistCategoryDescription`
+    - `optionsSiteWhitelistEnabled`
+    - `optionsSiteWhitelistEnabledDescription`
+    - `optionsSiteWhitelistContent`
+    - `optionsSiteWhitelistBasicView`
+    - `optionsSiteWhitelistRawView`
+    - `optionsSiteWhitelistSaveRaw`
+    - `optionsSiteWhitelistAddItem`
+    - `optionsSiteWhitelistUserAgent`
+    - `optionsSiteWhitelistEditItem`
+    - `optionsSiteWhitelistRemoveItem`
+    - `optionsSiteWhitelistInvalidMatchPattern`
+    - `popupWhitelistNotWhitelisted`
+    - `popupWhitelistAddToWhitelist`
+    - `popupCastMenuTitle`
+    - `popupStopMenuTitle`
 
--   `nl`
+- `nl`
 
-    -   `optionsBridgeBackupEnabled`
-    -   `optionsBridgeCompatible`
-    -   `optionsBridgeLikelyCompatible`
-    -   `optionsBridgeIncompatible`
-    -   `optionsOptionRecommended`
-    -   `optionsMirroringCategoryName`
-    -   `optionsMirroringCategoryDescription`
-    -   `optionsMirroringEnabled`
-    -   `optionsMirroringAppId`
-    -   `optionsSiteWhitelistCategoryName`
-    -   `optionsSiteWhitelistCategoryDescription`
-    -   `optionsSiteWhitelistEnabled`
-    -   `optionsSiteWhitelistEnabledDescription`
-    -   `optionsSiteWhitelistContent`
-    -   `optionsSiteWhitelistBasicView`
-    -   `optionsSiteWhitelistRawView`
-    -   `optionsSiteWhitelistSaveRaw`
-    -   `optionsSiteWhitelistAddItem`
-    -   `optionsSiteWhitelistUserAgent`
-    -   `optionsSiteWhitelistEditItem`
-    -   `optionsSiteWhitelistRemoveItem`
-    -   `optionsSiteWhitelistInvalidMatchPattern`
-    -   `popupWhitelistNotWhitelisted`
-    -   `popupWhitelistAddToWhitelist`
-    -   `popupMediaTypeAppNotFound`
-    -   `popupCastMenuTitle`
-    -   `popupStopMenuTitle`
+    - `optionsBridgeBackupEnabled`
+    - `optionsBridgeCompatible`
+    - `optionsBridgeLikelyCompatible`
+    - `optionsBridgeIncompatible`
+    - `optionsOptionRecommended`
+    - `optionsMirroringCategoryName`
+    - `optionsMirroringCategoryDescription`
+    - `optionsMirroringEnabled`
+    - `optionsMirroringAppId`
+    - `optionsSiteWhitelistCategoryName`
+    - `optionsSiteWhitelistCategoryDescription`
+    - `optionsSiteWhitelistEnabled`
+    - `optionsSiteWhitelistEnabledDescription`
+    - `optionsSiteWhitelistContent`
+    - `optionsSiteWhitelistBasicView`
+    - `optionsSiteWhitelistRawView`
+    - `optionsSiteWhitelistSaveRaw`
+    - `optionsSiteWhitelistAddItem`
+    - `optionsSiteWhitelistUserAgent`
+    - `optionsSiteWhitelistEditItem`
+    - `optionsSiteWhitelistRemoveItem`
+    - `optionsSiteWhitelistInvalidMatchPattern`
+    - `popupWhitelistNotWhitelisted`
+    - `popupWhitelistAddToWhitelist`
+    - `popupMediaTypeAppNotFound`
+    - `popupCastMenuTitle`
+    - `popupStopMenuTitle`
 
--   `no`
-    -   `optionsSiteWhitelistCategoryName`
-    -   `optionsSiteWhitelistCategoryDescription`
-    -   `optionsSiteWhitelistEnabled`
-    -   `optionsSiteWhitelistEnabledDescription`
-    -   `optionsSiteWhitelistContent`
-    -   `optionsSiteWhitelistBasicView`
-    -   `optionsSiteWhitelistRawView`
-    -   `optionsSiteWhitelistSaveRaw`
-    -   `optionsSiteWhitelistAddItem`
-    -   `optionsSiteWhitelistUserAgent`
-    -   `optionsSiteWhitelistEditItem`
-    -   `optionsSiteWhitelistRemoveItem`
-    -   `optionsSiteWhitelistInvalidMatchPattern`
-    -   `popupWhitelistNotWhitelisted`
-    -   `popupWhitelistAddToWhitelist`
-    -   `popupCastMenuTitle`
-    -   `popupStopMenuTitle`
+- `no`
+    - `optionsSiteWhitelistCategoryName`
+    - `optionsSiteWhitelistCategoryDescription`
+    - `optionsSiteWhitelistEnabled`
+    - `optionsSiteWhitelistEnabledDescription`
+    - `optionsSiteWhitelistContent`
+    - `optionsSiteWhitelistBasicView`
+    - `optionsSiteWhitelistRawView`
+    - `optionsSiteWhitelistSaveRaw`
+    - `optionsSiteWhitelistAddItem`
+    - `optionsSiteWhitelistUserAgent`
+    - `optionsSiteWhitelistEditItem`
+    - `optionsSiteWhitelistRemoveItem`
+    - `optionsSiteWhitelistInvalidMatchPattern`
+    - `popupWhitelistNotWhitelisted`
+    - `popupWhitelistAddToWhitelist`
+    - `popupCastMenuTitle`
+    - `popupStopMenuTitle`
+
+- `it`
+    - `popupMediaTypeFile`
+    - `popupCastingButtonTitle`
+    - `optionsBridgeOlderAction`
+    - `optionsBridgeNewerAction`
+    - `optionsBridgeUpdateCheck`
+    - `optionsBridgeUpdateChecking`
+    - `optionsBridgeBackupEnabled`
+    - `optionsBridgeBackupEnabledDescription`
+    - `optionsMediaCategoryName`
+    - `optionsMediaCategoryDescription`
+    - `optionsMediaCategoryDescription`
+    - `optionsMediaEnabled`
+    - `optionsMediaSyncElement`
+    - `optionsMediaSyncElementDescription`
+    - `optionsMediaStopOnUnload`
+    - `optionsLocalMediaCategoryName`
+    - `optionsLocalMediaCategoryDescription`
+    - `optionsLocalMediaEnabled`
+    - `optionsLocalMediaServerPort`
+    - `optionsReceiverSelectorCategoryName`
+    - `optionsReceiverSelectorCategoryDescription`
+    - `optionsReceiverSelectorWaitForConnection`
+    - `optionsReceiverSelectorWaitForConnectionDescription`
+    - `optionsReceiverSelectorCloseIfFocusLost`
+    - `optionsSiteWhitelistCategoryName`
+    - `optionsSiteWhitelistCategoryDescription`
+    - `optionsSiteWhitelistEnabled`
+    - `optionsSiteWhitelistEnabledDescription`
+    - `optionsSiteWhitelistContent`
+    - `optionsSiteWhitelistBasicView`
+    - `optionsSiteWhitelistRawView`
+    - `optionsSiteWhitelistSaveRaw`
+    - `optionsSiteWhitelistAddItem`
+    - `optionsSiteWhitelistUserAgent`
+    - `optionsSiteWhitelistEditItem`
+    - `optionsSiteWhitelistRemoveItem`
+    - `optionsSiteWhitelistInvalidDuplicatePattern`
+    - `optionsSiteWhitelistKnownAppsCustomApp`
+    - `optionsMirroringCategoryName`
+    - `optionsMirroringCategoryDescription`
+    - `optionsMirroringEnabled`
+    - `optionsMirroringAppId`
+    - `optionsMirroringAppIdDescription`
+    - `optionsOptionRecommended`
+    - `optionsReset`
+    - `optionsSave`
+    - `optionsSaved`
+
+</details>
 
 ### NSIS Installer Localization
 
diff --git a/ext/src/_locales/it/messages.json b/ext/src/_locales/it/messages.json
new file mode 100644
index 0000000..ed37d82
--- /dev/null
+++ b/ext/src/_locales/it/messages.json
@@ -0,0 +1,168 @@
+{
+    "extensionDescription": {
+        "message": "Fornisce il supporto a web app Chromecast (come Netflix o BBC iPlayer), video HTML5 e condivisione tab/schermo. ",
+        "description": "Description of the extension shown in the add-ons manager."
+    },
+    "popupWhitelistNotWhitelisted": {
+        "message": "$appName$ non è nella Whitelist",
+        "description": "Receiver selector whitelist suggestion banner label.",
+        "placeholders": {
+            "appName": {
+                "content": "$1",
+                "example": "Netflix"
+            }
+        }
+    },
+    "popupWhitelistAddToWhitelist": {
+        "message": "Aggiungi alla Whitelist",
+        "description": "Receiver selector whitelist suggestion banner button label."
+    },
+    "popupMediaTypeApp": {
+        "message": "l'app del sito corrente",
+        "description": "Receiver selector media type <option> text for current site's sender application."
+    },
+    "popupMediaTypeAppNotFound": {
+        "message": "l'app del sito corrente (non trovato)",
+        "description": "Receiver selector media type <option> text for current site's sender application if none found."
+    },
+    "popupMediaTypeAppMedia": {
+        "message": "questo media ",
+        "description": "Receiver selector media type <option> text for media casting."
+    },
+    "popupMediaTypeTab": {
+        "message": "Tab",
+        "description": "Receiver selector media type <option> text for current tab."
+    },
+    "popupMediaTypeScreen": {
+        "message": "Schermo",
+        "description": "Receiver selector media type <option> text for screen."
+    },
+    "popupMediaSelectCastLabel": {
+        "message": "Cast",
+        "description": "(Cast) <select> to:"
+    },
+    "popupMediaSelectToLabel": {
+        "message": "a:",
+        "description": "Cast <select> (to:)"
+    },
+    "popupNoReceiversFound": {
+        "message": "Nessun ricevitore trovato",
+        "description": "Message displayed in the receiver selector if there are no available receivers."
+    },
+    "popupCastButtonTitle": {
+        "message": "Cast",
+        "description": "Button text for each receiver entry in the receiver selector."
+    },
+    "popupCastMenuTitle": {
+        "message": "Cast a \"$deviceName$\"",
+        "description": "Menu text for cast item in context menu for receivers in receiver selector.",
+        "placeholders": {
+            "deviceName": {
+                "content": "$1",
+                "example": "Living Room TV"
+            }
+        }
+    },
+    "popupStopMenuTitle": {
+        "message": "Stop \"$appName$\" su \"$deviceName$\"",
+        "description": "Menu text for stop item in context menu for receivers in receiver selector.",
+        "placeholders": {
+            "appName": {
+                "content": "$1",
+                "example": "Netflix"
+            },
+            "deviceName": {
+                "content": "$2",
+                "example": "Living Room TV"
+            }
+        }
+    },
+    "contextAddToWhitelist": {
+        "message": "Aggiungi alla Whitelist",
+        "description": "Top-level whitelist context menu item title."
+    },
+    "contextAddToWhitelistRecommended": {
+        "message": "Aggiungi $matchPattern$ (Raccomandato)",
+        "description": "Context menu item title for recomended match pattern.",
+        "placeholders": {
+            "matchPattern": {
+                "content": "$1",
+                "example": "https://example.com/*"
+            }
+        }
+    },
+    "contextAddToWhitelistAdvancedAdd": {
+        "message": "Aggiungi $matchPattern$",
+        "description": "Context menu item title for all other match patterns.",
+        "placeholders": {
+            "matchPattern": {
+                "content": "$1",
+                "example": "*://*.example.com/*"
+            }
+        }
+    },
+    "optionsBridgeLoading": {
+        "message": "Caricamento info bridge...",
+        "description": "Loading placeholder text for bridge section on options page."
+    },
+    "optionsBridgeFoundStatusTitle": {
+        "message": "Bridge trovato",
+        "description": "Bridge OK status title text."
+    },
+    "optionsBridgeIssueStatusTitle": {
+        "message": "Problema con il bridge",
+        "description": "Bridge error status title text."
+    },
+    "optionsBridgeNotFoundStatusTitle": {
+        "message": "Bridge non trovato",
+        "description": "Bridge missing status title text."
+    },
+    "optionsBridgeNotFoundStatusText": {
+        "message": "Prova a scaricare e installare l'ultima versione.",
+        "description": "Bridge not found additional description text"
+    },
+    "optionsBridgeStatsName": {
+        "message": "Nome:",
+        "description": "Bridge stats name row title."
+    },
+    "optionsBridgeStatsVersion": {
+        "message": "Versione:",
+        "description": "Bridge stats version row title."
+    },
+    "optionsBridgeStatsRecommendedAction": {
+        "message": "Azione raccomandata:",
+        "description": "Bridge stats recommended action row title."
+    },
+    "optionsBridgeCompatible": {
+        "message": "Compatibile:",
+        "description": "Compatibility status is definitely compatible."
+    },
+    "optionsBridgeLikelyCompatible": {
+        "message": "Probabilmente compatibile:",
+        "description": "Compatibility status is probably compatible."
+    },
+    "optionsBridgeIncompatible": {
+        "message": "Incompatibile:",
+        "description": "Compatibility status is definitely incompatible."
+    },
+    "optionsBridgeNoAction": {
+        "message": "Nessuna azione richiesta:",
+        "description": "Recommended action for when both bridge and extension versions are compatible or likely compatible."
+    },
+    "optionsBridgeUpdateStatusNoUpdates": {
+        "message": "Nessun aggiornamento disponibile",
+        "description": "Update status if no updates are found."
+    },
+    "optionsBridgeUpdateStatusError": {
+        "message": "Errore durante la ricerca degli aggiornamenti",
+        "description": "Update status if an error was encountered checking for updates."
+    },
+    "optionsBridgeUpdateAvailable": {
+        "message": "Aggiornamento disponibile:",
+        "description": "Update status if an update was found."
+    },
+    "optionsBridgeUpdate": {
+        "message": "Aggiorna ora...",
+        "description": "Update now button title. Ellipsis indicates additional information as it triggers an update window popup."
+    }
+}