diff --git a/MarkEditMac/Resources/Localizable.xcstrings b/MarkEditMac/Resources/Localizable.xcstrings
index 34baefab..7c64cda9 100644
--- a/MarkEditMac/Resources/Localizable.xcstrings
+++ b/MarkEditMac/Resources/Localizable.xcstrings
@@ -177,6 +177,23 @@
         }
       }
     },
+    "Actions" : {
+      "comment" : "Toolbar menu of extension manager actions",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "操作"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "操作"
+          }
+        }
+      }
+    },
     "Active line indicator" : {
       "comment" : "Option to show active line indicator",
       "localizations" : {
@@ -639,6 +656,23 @@
         }
       }
     },
+    "Couldn’t reach the extension registry." : {
+      "comment" : "Error shown when the registry can't be loaded",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "无法连接扩展目录。"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "無法連接擴充功能目錄。"
+          }
+        }
+      }
+    },
     "Create New Document" : {
       "localizations" : {
         "zh-Hans" : {
@@ -875,6 +909,23 @@
         }
       }
     },
+    "Discover" : {
+      "comment" : "Extension manager mode: browse the registry",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "发现"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "發現"
+          }
+        }
+      }
+    },
     "Document" : {
       "comment" : "Statistics mode: full document",
       "localizations" : {
@@ -943,6 +994,23 @@
         }
       }
     },
+    "Enabled" : {
+      "comment" : "Toggle title for enabling an installed extension",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "已启用"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "已啟用"
+          }
+        }
+      }
+    },
     "Enter the line number and hit return" : {
       "comment" : "Help text for goto line window",
       "localizations" : {
@@ -1494,6 +1562,23 @@
         }
       }
     },
+    "Homepage" : {
+      "comment" : "Link to an extension's homepage",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "主页"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "首頁"
+          }
+        }
+      }
+    },
     "Horizontal Rule" : {
       "comment" : "Toolbar item to insert horizontal rule",
       "localizations" : {
@@ -1748,6 +1833,57 @@
         }
       }
     },
+    "Install Extension from URL" : {
+      "comment" : "Title for the install-from-URL prompt",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "从 URL 安装扩展"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "從 URL 安裝擴充功能"
+          }
+        }
+      }
+    },
+    "Install from URL…" : {
+      "comment" : "Menu item to install an extension from a URL",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "从 URL 安装…"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "從 URL 安裝…"
+          }
+        }
+      }
+    },
+    "Installed" : {
+      "comment" : "Extension manager mode: installed extensions",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "已安装"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "已安裝"
+          }
+        }
+      }
+    },
     "Italic" : {
       "comment" : "Toolbar item to toggle italic",
       "localizations" : {
@@ -2009,6 +2145,23 @@
         }
       }
     },
+    "MarkEdit Extensions" : {
+      "comment" : "Title of the extension manager window",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "MarkEdit 扩展功能"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "MarkEdit 擴充功能"
+          }
+        }
+      }
+    },
     "Missing active document to proceed." : {
       "localizations" : {
         "zh-Hans" : {
@@ -2160,6 +2313,40 @@
         }
       }
     },
+    "No extensions found." : {
+      "comment" : "Empty state for the Discover list",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "未找到扩展。"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "未找到擴充功能。"
+          }
+        }
+      }
+    },
+    "No extensions installed." : {
+      "comment" : "Empty state for installed extensions",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "未安装扩展。"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "未安裝擴充功能。"
+          }
+        }
+      }
+    },
     "No versions match the specified condition." : {
       "comment" : "Alert title for no versions found",
       "localizations" : {
@@ -2245,6 +2432,23 @@
         }
       }
     },
+    "Open Scripts Folder" : {
+      "comment" : "Menu item to reveal the extensions scripts folder",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "打开脚本目录"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "打開指令碼目錄"
+          }
+        }
+      }
+    },
     "option-esc" : {
       "shouldTranslate" : false
     },
@@ -2469,6 +2673,40 @@
         }
       }
     },
+    "Refresh" : {
+      "comment" : "Menu item to refetch the extension registry",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "刷新"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "重新整理"
+          }
+        }
+      }
+    },
+    "Refreshing…" : {
+      "comment" : "State shown while the extension list is being refreshed",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "正在刷新…"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "重新整理中…"
+          }
+        }
+      }
+    },
     "Regular Expression" : {
       "comment" : "Toggle regular expression for search",
       "localizations" : {
@@ -2537,6 +2775,23 @@
         }
       }
     },
+    "Relaunch to apply your changes." : {
+      "comment" : "Notice shown when extension changes need a relaunch",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "重新启动以应用更改。"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "重新啟動以套用變更。"
+          }
+        }
+      }
+    },
     "Relaxed" : {
       "comment" : "Relaxed line spacing",
       "localizations" : {
@@ -2656,6 +2911,40 @@
         }
       }
     },
+    "Retry" : {
+      "comment" : "Button to retry reaching the extension registry",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "重试"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "重試"
+          }
+        }
+      }
+    },
+    "Reveal" : {
+      "comment" : "Button title to reveal an extension's script file in Finder",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "显示"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "顯示"
+          }
+        }
+      }
+    },
     "Revert to This Version" : {
       "comment" : "Title for button to select a file version",
       "localizations" : {
@@ -2978,6 +3267,23 @@
         }
       }
     },
+    "Submit an Extension…" : {
+      "comment" : "Menu item to open the extension contributing guide",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "提交扩展…"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "提交擴充功能…"
+          }
+        }
+      }
+    },
     "Suggest while typing" : {
       "comment" : "Whether to suggest while typing",
       "localizations" : {
@@ -3267,6 +3573,23 @@
         }
       }
     },
+    "This removes its script from the scripts folder." : {
+      "comment" : "Message shown when confirming an extension uninstall",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "这会从脚本目录中移除它的脚本。"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "這會從指令碼目錄中移除它的指令碼。"
+          }
+        }
+      }
+    },
     "This source is not reviewed by MarkEdit. Only continue if you trust it." : {
       "comment" : "Caution shown before installing an extension from a raw URL",
       "localizations" : {
@@ -3386,6 +3709,23 @@
         }
       }
     },
+    "Turn off to keep the extension installed but inactive" : {
+      "comment" : "Tooltip explaining the enable switch",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "关闭后仍保留扩展，但使其不生效"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "關閉後仍保留擴充功能，但使其不啟用"
+          }
+        }
+      }
+    },
     "Unfold" : {
       "comment" : "Phrase used in CodeMirror to unfold a piece of text",
       "localizations" : {
@@ -3437,6 +3777,40 @@
         }
       }
     },
+    "Uninstall" : {
+      "comment" : "Button title to uninstall an extension",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "卸载"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "解除安裝"
+          }
+        }
+      }
+    },
+    "Uninstall “%@”?" : {
+      "comment" : "Title (format) to confirm uninstalling an extension",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "要卸载“%@”吗？"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "要解除安裝“%@”嗎？"
+          }
+        }
+      }
+    },
     "Update" : {
       "comment" : "Button title to install extension updates",
       "localizations" : {
@@ -3454,6 +3828,23 @@
         }
       }
     },
+    "Update All" : {
+      "comment" : "Menu item to update all extensions with available updates",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "全部更新"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "全部更新"
+          }
+        }
+      }
+    },
     "Update File Content" : {
       "localizations" : {
         "zh-Hans" : {
@@ -3487,6 +3878,23 @@
         }
       }
     },
+    "Update to %@" : {
+      "comment" : "Button title (format) to update an extension to a version",
+      "localizations" : {
+        "zh-Hans" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "更新到 %@"
+          }
+        },
+        "zh-Hant" : {
+          "stringUnit" : {
+            "state" : "translated",
+            "value" : "更新到 %@"
+          }
+        }
+      }
+    },
     "Updates file content of the active document; throws an error if no editor is opened." : {
       "localizations" : {
         "zh-Hans" : {
diff --git a/MarkEditMac/Sources/Extension/ExtensionInstaller.swift b/MarkEditMac/Sources/Extension/ExtensionInstaller.swift
index 23d978bd..abbd00c6 100644
--- a/MarkEditMac/Sources/Extension/ExtensionInstaller.swift
+++ b/MarkEditMac/Sources/Extension/ExtensionInstaller.swift
@@ -161,5 +161,32 @@ extension Localized {
     static let updateButton = String(localized: "Update", comment: "Button title to install extension updates")
     static let updatedTitle = String(localized: "Extensions Updated", comment: "Title shown after extensions are updated")
     static let updatedMessage = String(localized: "Relaunch MarkEdit to use the updated extensions.", comment: "Message shown after extensions are updated")
+
+    // MARK: - Manager UI
+
+    static let managerTitle = String(localized: "MarkEdit Extensions", comment: "Title of the extension manager window")
+    static let installed = String(localized: "Installed", comment: "Extension manager mode: installed extensions")
+    static let discover = String(localized: "Discover", comment: "Extension manager mode: browse the registry")
+    static let enabled = String(localized: "Enabled", comment: "Toggle title for enabling an installed extension")
+    static let enabledTooltip = String(localized: "Turn off to keep the extension installed but inactive", comment: "Tooltip explaining the enable switch")
+    static let uninstall = String(localized: "Uninstall", comment: "Button title to uninstall an extension")
+    static let reveal = String(localized: "Reveal", comment: "Button title to reveal an extension's script file in Finder")
+    static let uninstallConfirmFormat = String(localized: "Uninstall “%@”?", comment: "Title (format) to confirm uninstalling an extension")
+    static let uninstallConfirmMessage = String(localized: "This removes its script from the scripts folder.", comment: "Message shown when confirming an extension uninstall")
+    static let updateToFormat = String(localized: "Update to %@", comment: "Button title (format) to update an extension to a version")
+    static let homepage = String(localized: "Homepage", comment: "Link to an extension's homepage")
+    static let actions = String(localized: "Actions", comment: "Toolbar menu of extension manager actions")
+    static let installFromURL = String(localized: "Install from URL…", comment: "Menu item to install an extension from a URL")
+    static let installFromURLTitle = String(localized: "Install Extension from URL", comment: "Title for the install-from-URL prompt")
+    static let openScriptsFolder = String(localized: "Open Scripts Folder", comment: "Menu item to reveal the extensions scripts folder")
+    static let refresh = String(localized: "Refresh", comment: "Menu item to refetch the extension registry")
+    static let refreshing = String(localized: "Refreshing…", comment: "State shown while the extension list is being refreshed")
+    static let updateAll = String(localized: "Update All", comment: "Menu item to update all extensions with available updates")
+    static let submitExtension = String(localized: "Submit an Extension…", comment: "Menu item to open the extension contributing guide")
+    static let relaunchNotice = String(localized: "Relaunch to apply your changes.", comment: "Notice shown when extension changes need a relaunch")
+    static let retry = String(localized: "Retry", comment: "Button to retry reaching the extension registry")
+    static let registryUnreachable = String(localized: "Couldn’t reach the extension registry.", comment: "Error shown when the registry can't be loaded")
+    static let emptyInstalled = String(localized: "No extensions installed.", comment: "Empty state for installed extensions")
+    static let emptyDiscover = String(localized: "No extensions found.", comment: "Empty state for the Discover list")
   }
 }
diff --git a/MarkEditMac/Sources/Main/AppResources.swift b/MarkEditMac/Sources/Main/AppResources.swift
index ecc2ad7e..e0827ca6 100644
--- a/MarkEditMac/Sources/Main/AppResources.swift
+++ b/MarkEditMac/Sources/Main/AppResources.swift
@@ -251,6 +251,8 @@ enum Icons {
   static let characterCursorIbeam = "character.cursor.ibeam"
   static let chartPie = "chart.pie"
   static let curlybracesSquare = "curlybraces.square"
+  static let ellipsisCircle = "ellipsis.circle"
+  static let exclamationmarkBubbleFill = "exclamationmark.bubble.fill"
   static let gearshape = "gearshape"
   static let italic = "italic"
 
@@ -276,7 +278,11 @@ enum Icons {
     "number"
   }
 
+  static let paintpalette = "paintpalette"
   static let photo = "photo"
+  static let puzzlepieceExtension = "puzzlepiece.extension"
+  static let shippingbox = "shippingbox"
+  static let sparkles = "sparkles"
   static let squareAndArrowUp = "square.and.arrow.up"
   static let squareSplit1x2 = "square.split.1x2"
   static let strikethrough = "strikethrough"
@@ -284,6 +290,7 @@ enum Icons {
   static let textQuote = "text.quote"
   static let textformat = "textformat"
   static let wandAndSparkles = "wand.and.sparkles"
+  static let wifiSlash = "wifi.slash"
 }
 
 extension EditorLocalizable {