diff --git a/build/Gruntfile.coffee b/build/Gruntfile.coffee
index 33396fa0a..e8d1a76ff 100644
--- a/build/Gruntfile.coffee
+++ b/build/Gruntfile.coffee
@@ -174,9 +174,6 @@ module.exports = (grunt) ->
     glob_to_multiple:
       expand: true
       src: [
-        'menus/*.cson'
-        'keymaps/*.cson'
-        'keymaps/templates/*.cson'
         'static/**/*.cson'
       ]
       dest: appDir
diff --git a/build/tasks/copy-files-for-build-task.coffee b/build/tasks/copy-files-for-build-task.coffee
index b0bb6f3cd..12719d0eb 100644
--- a/build/tasks/copy-files-for-build-task.coffee
+++ b/build/tasks/copy-files-for-build-task.coffee
@@ -171,6 +171,8 @@ module.exports = (grunt) ->
     cp 'spec', path.join(appDir, 'spec')
     cp 'src', path.join(appDir, 'src'), filter: /.+\.(cson|coffee|cjsx|jsx)$/
     cp 'static', path.join(appDir, 'static')
+    cp 'keymaps', path.join(appDir, 'keymaps')
+    cp 'menus', path.join(appDir, 'menus')
 
     # Move all of the node modules inside /apm/node_modules to new-app/apm/node_modules
     apmInstallDir = path.resolve(appDir, '..', 'new-app', 'apm')
diff --git a/dot-nylas/keymap.cson b/dot-nylas/keymap.cson
deleted file mode 100644
index 7c983a759..000000000
--- a/dot-nylas/keymap.cson
+++ /dev/null
@@ -1,27 +0,0 @@
-# Your keymap
-#
-# N1 keymaps work in conjunction with the {KeyCommandsRegion} React
-# component.
-#
-# A key, or sequence of keys is first mapped to a "command".
-#
-# The "command" is then mapped to a callback function within your React
-# component or store.
-#
-# The keyboard -> command mapping is defined in this `.cson` file. Each
-# mapping is scoped under the component that it applies to by matching the
-# root-level CSS class of that component.
-#
-# Any global, top-level mappings are scoped under the `body` selector.
-#
-# For example:
-#
-# 'body':
-#   'ctrl+c': 'application:new-message'
-#
-# '.my-custom-package':
-#   'ctrl+p': 'myPackage:customAction'
-#
-# This file uses CoffeeScript Object Notation (CSON).
-# If you are unfamiliar with CSON, you can read more about it here:
-# https://github.com/bevry/cson#what-is-cson
diff --git a/dot-nylas/keymap.json b/dot-nylas/keymap.json
new file mode 100644
index 000000000..e69de29bb
diff --git a/internal_packages/message-view-on-github/keymaps/github.cson b/internal_packages/message-view-on-github/keymaps/github.json
similarity index 100%
rename from internal_packages/message-view-on-github/keymaps/github.cson
rename to internal_packages/message-view-on-github/keymaps/github.json
diff --git a/internal_packages/thread-search/keymaps/search-bar.cson b/internal_packages/thread-search/keymaps/search-bar.json
similarity index 100%
rename from internal_packages/thread-search/keymaps/search-bar.cson
rename to internal_packages/thread-search/keymaps/search-bar.json
diff --git a/menus/linux.cson b/menus/linux.cson
deleted file mode 100644
index 5325d890c..000000000
--- a/menus/linux.cson
+++ /dev/null
@@ -1,81 +0,0 @@
-'menu': [
-  {
-    label: '&File'
-    submenu: [
-      { label: '&New Message', command: 'application:new-message' }
-      { type: 'separator' }
-      { label: 'Add Account...', command: 'application:add-account' }
-      { label: 'Clos&e Window', command: 'window:close' }
-      { type: 'separator' }
-      { label: 'Print Current Thread', command: 'core:print-thread' }
-      { type: 'separator' }
-      { label: 'Quit', command: 'application:quit' }
-    ]
-  }
-
-  {
-    label: '&Edit'
-    submenu: [
-      { label: '&Undo', command: 'core:undo' }
-      { label: '&Redo', command: 'core:redo' }
-      { type: 'separator' }
-      { label: '&Cut', command: 'core:cut' }
-      { label: 'C&opy', command: 'core:copy' }
-      { label: '&Paste', command: 'core:paste' }
-      { label: 'Paste and Match Style', command: 'core:paste-and-match-style' }
-      { label: 'Select &All', command: 'core:select-all' }
-      { type: 'separator' }
-      { label: 'Find', submenu: [
-        { label: 'Find in Thread...', command: 'core:find-in-thread' }
-        { label: 'Find Next', command: 'core:find-in-thread-next' }
-        { label: 'Find Previous', command: 'core:find-in-thread-previous' }
-      ] }
-      { type: 'separator' }
-      { label: 'Preferences', command: 'application:open-preferences' }
-      { label: 'Change Theme...', command: 'window:launch-theme-picker' }
-      { label: 'Install Theme...', command: 'application:install-package' }
-    ]
-  }
-
-  {
-    label: '&View'
-    submenu: [
-      { label: 'Single Panel Mode', type: 'checkbox', command: 'application:select-list-mode' }
-      { label: 'Two Panel Mode', type: 'checkbox', command: 'application:select-split-mode' }
-      { type: 'separator' }
-      { label: 'Toggle &Full Screen', command: 'window:toggle-full-screen' }
-    ]
-  }
-  {
-    label: 'Developer'
-    submenu: [
-      { label: 'Run with &Debug Flags', type: 'checkbox', command: 'application:toggle-dev' }
-      { type: 'separator' }
-      { label: 'Reload', command: 'window:reload' }
-      { label: 'Toggle Developer &Tools', command: 'window:toggle-dev-tools' }
-      { label: 'Toggle Component Regions', command: 'window:toggle-component-regions' }
-      { label: 'Toggle Screenshot Mode', command: 'window:toggle-screenshot-mode' }
-      { type: 'separator' }
-      { label: 'Open Activity Window', command: 'application:show-work-window' }
-      { type: 'separator' }
-      { label: 'Create a Plugin...', command: 'application:create-package' }
-      { label: 'Install a Plugin...', command: 'application:install-package' }
-      { type: 'separator' }
-      { label: 'Run Plugin &Specs...', command: 'application:run-package-specs' }
-      { label: 'Run &N1 Specs', command: 'application:run-all-specs' }
-      { type: 'separator' }
-      { label: 'Open Detailed Logs', command: 'window:open-errorlogger-logs' }
-    ]
-  }
-  {
-    label: '&Help'
-    submenu: [
-      { label: "VERSION", enabled: false }
-      { type: 'separator' }
-      { label: 'Nylas N1 Help', command: 'application:view-help' }
-    ]
-  }
-]
-
-'context-menu':[
-]
diff --git a/menus/linux.json b/menus/linux.json
new file mode 100644
index 000000000..62e9fc31d
--- /dev/null
+++ b/menus/linux.json
@@ -0,0 +1,80 @@
+{
+  "menu": [
+    {
+      "label": "&File",
+      "submenu": [
+        { "label": "&New Message", "command": "application:new-message" },
+        { "type": "separator" },
+        { "label": "Add Account...", "command": "application:add-account" },
+        { "label": "Clos&e Window", "command": "window:close" },
+        { "type": "separator" },
+        { "label": "Print Current Thread", "command": "core:print-thread" },
+        { "type": "separator" },
+        { "label": "Quit", "command": "application:quit" }
+      ]
+    },
+
+    {
+      "label": "&Edit",
+      "submenu": [
+        { "label": "&Undo", "command": "core:undo" },
+        { "label": "&Redo", "command": "core:redo" },
+        { "type": "separator" },
+        { "label": "&Cut", "command": "core:cut" },
+        { "label": "C&opy", "command": "core:copy" },
+        { "label": "&Paste", "command": "core:paste" },
+        { "label": "Paste and Match Style", "command": "core:paste-and-match-style" },
+        { "label": "Select &All", "command": "core:select-all" },
+        { "type": "separator" },
+        { "label": "Find", "submenu": [
+          { "label": "Find in Thread...", "command": "core:find-in-thread" },
+          { "label": "Find Next", "command": "core:find-in-thread-next" },
+          { "label": "Find Previous", "command": "core:find-in-thread-previous" }
+        ]},
+        { "type": "separator" },
+        { "label": "Preferences", "command": "application:open-preferences" },
+        { "label": "Change Theme...", "command": "window:launch-theme-picker" },
+        { "label": "Install Theme...", "command": "application:install-package" }
+      ]
+    },
+
+    {
+      "label": "&View",
+      "submenu": [
+        { "label": "Single Panel Mode", "type": "checkbox", "command": "application:select-list-mode" },
+        { "label": "Two Panel Mode", "type": "checkbox", "command": "application:select-split-mode" },
+        { "type": "separator" },
+        { "label": "Toggle &Full Screen", "command": "window:toggle-full-screen" }
+      ]
+    },
+    {
+      "label": "Developer",
+      "submenu": [
+        { "label": "Run with &Debug Flags", "type": "checkbox", "command": "application:toggle-dev" },
+        { "type": "separator" },
+        { "label": "Reload", "command": "window:reload" },
+        { "label": "Toggle Developer &Tools", "command": "window:toggle-dev-tools" },
+        { "label": "Toggle Component Regions", "command": "window:toggle-component-regions" },
+        { "label": "Toggle Screenshot Mode", "command": "window:toggle-screenshot-mode" },
+        { "type": "separator" },
+        { "label": "Open Activity Window", "command": "application:show-work-window" },
+        { "type": "separator" },
+        { "label": "Create a Plugin...", "command": "application:create-package" },
+        { "label": "Install a Plugin...", "command": "application:install-package" },
+        { "type": "separator" },
+        { "label": "Run Plugin &Specs...", "command": "application:run-package-specs" },
+        { "label": "Run &N1 Specs", "command": "application:run-all-specs" },
+        { "type": "separator" },
+        { "label": "Open Detailed Logs", "command": "window:open-errorlogger-logs" }
+      ]
+    },
+    {
+      "label": "&Help",
+      "submenu": [
+        { "label": "VERSION", "enabled": false },
+        { "type": "separator" },
+        { "label": "Nylas N1 Help", "command": "application:view-help" }
+      ]
+    }
+  ]
+}
diff --git a/menus/win32.cson b/menus/win32.cson
deleted file mode 100644
index d83471dfd..000000000
--- a/menus/win32.cson
+++ /dev/null
@@ -1,75 +0,0 @@
-'menu': [
-  { label: 'Add Account...', command: 'application:add-account' }
-  {
-    label: '&Edit'
-    submenu: [
-      { label: '&Undo', command: 'core:undo' }
-      { label: '&Redo', command: 'core:redo' }
-      { type: 'separator' }
-      { label: 'Cu&t', command: 'core:cut' }
-      { label: '&Copy', command: 'core:copy' }
-      { label: '&Paste', command: 'core:paste' }
-      { label: 'Paste and Match Style', command: 'core:paste-and-match-style' }
-      { label: 'Select &All', command: 'core:select-all' }
-      { type: 'separator' }
-      { label: 'Find', submenu: [
-        { label: 'Find in Thread...', command: 'core:find-in-thread' }
-        { label: 'Find Next', command: 'core:find-in-thread-next' }
-        { label: 'Find Previous', command: 'core:find-in-thread-previous' }
-      ] }
-    ]
-  }
-
-  {
-    label: '&View'
-    submenu: [
-      { label: 'Single Panel Mode', type: 'checkbox', command: 'application:select-list-mode' }
-      { label: 'Two Panel Mode', type: 'checkbox', command: 'application:select-split-mode' }
-      { type: 'separator' }
-      { label: 'Toggle &Full Screen', command: 'window:toggle-full-screen' }
-    ]
-  }
-  {
-    label: 'Developer'
-    submenu: [
-      { label: 'Run with &Debug Flags', type: 'checkbox', command: 'application:toggle-dev' }
-      { type: 'separator' }
-      { label: '&Reload', command: 'window:reload' }
-      { label: 'Toggle Developer &Tools', command: 'window:toggle-dev-tools' }
-      { label: 'Toggle Component Regions', command: 'window:toggle-component-regions' }
-      { label: 'Toggle Screenshot Mode', command: 'window:toggle-screenshot-mode' }
-      { type: 'separator' }
-      { label: 'Open Activity Window', command: 'application:show-work-window' }
-      { type: 'separator' }
-      { label: 'Create a Plugin...', command: 'application:create-package' }
-      { label: 'Install a Plugin...', command: 'application:install-package' }
-      { type: 'separator' }
-      { label: 'Run Plugin &Specs...', command: 'application:run-package-specs' }
-      { label: 'Run &N1 Specs', command: 'application:run-all-specs' }
-      { type: 'separator' }
-      { label: 'Open Detailed Logs', command: 'window:open-errorlogger-logs' }
-    ]
-  }
-  {
-    label: '&Help'
-    submenu: [
-      { label: 'VERSION', enabled: false }
-      { label: 'Restart and Install Update', command: 'application:install-update', visible: false}
-      { label: 'Check for Update', command: 'application:check-for-update', visible: false}
-      { label: 'Downloading Update', enabled: false, visible: false}
-      { type: 'separator' }
-      { label: 'Nylas N1 Help', command: 'application:view-help' }
-    ]
-  }
-  { type: 'separator' }
-  { label: 'Preferences', command: 'application:open-preferences' }
-  { label: 'Change Theme...', command: 'window:launch-theme-picker' }
-  { label: 'Install Theme...', command: 'application:install-package' }
-  { type: 'separator' }
-  { label: 'Print Current Thread', command: 'core:print-thread' }
-  { type: 'separator' }
-  { label: 'E&xit', command: 'application:quit' }
-]
-
-'context-menu':[
-]
diff --git a/menus/win32.json b/menus/win32.json
new file mode 100644
index 000000000..196c592ee
--- /dev/null
+++ b/menus/win32.json
@@ -0,0 +1,74 @@
+{
+  "menu": [
+    { "label": "Add Account...", "command": "application:add-account" },
+    {
+      "label": "&Edit",
+      "submenu": [
+        { "label": "&Undo", "command": "core:undo" },
+        { "label": "&Redo", "command": "core:redo" },
+        { "type": "separator" },
+        { "label": "Cu&t", "command": "core:cut" },
+        { "label": "&Copy", "command": "core:copy" },
+        { "label": "&Paste", "command": "core:paste" },
+        { "label": "Paste and Match Style", "command": "core:paste-and-match-style" },
+        { "label": "Select &All", "command": "core:select-all" },
+        { "type": "separator" },
+        { "label": "Find", "submenu": [
+          { "label": "Find in Thread...", "command": "core:find-in-thread" },
+          { "label": "Find Next", "command": "core:find-in-thread-next" },
+          { "label": "Find Previous", "command": "core:find-in-thread-previous" }
+        ] }
+      ]
+    },
+
+    {
+      "label": "&View",
+      "submenu": [
+        { "label": "Single Panel Mode", "type": "checkbox", "command": "application:select-list-mode" },
+        { "label": "Two Panel Mode", "type": "checkbox", "command": "application:select-split-mode" },
+        { "type": "separator" },
+        { "label": "Toggle &Full Screen", "command": "window:toggle-full-screen" }
+      ]
+    },
+    {
+      "label": "Developer",
+      "submenu": [
+        { "label": "Run with &Debug Flags", "type": "checkbox", "command": "application:toggle-dev" },
+        { "type": "separator" },
+        { "label": "&Reload", "command": "window:reload" },
+        { "label": "Toggle Developer &Tools", "command": "window:toggle-dev-tools" },
+        { "label": "Toggle Component Regions", "command": "window:toggle-component-regions" },
+        { "label": "Toggle Screenshot Mode", "command": "window:toggle-screenshot-mode" },
+        { "type": "separator" },
+        { "label": "Open Activity Window", "command": "application:show-work-window" },
+        { "type": "separator" },
+        { "label": "Create a Plugin...", "command": "application:create-package" },
+        { "label": "Install a Plugin...", "command": "application:install-package" },
+        { "type": "separator" },
+        { "label": "Run Plugin &Specs...", "command": "application:run-package-specs" },
+        { "label": "Run &N1 Specs", "command": "application:run-all-specs" },
+        { "type": "separator" },
+        { "label": "Open Detailed Logs", "command": "window:open-errorlogger-logs" }
+      ]
+    },
+    {
+      "label": "&Help",
+      "submenu": [
+        { "label": "VERSION", "enabled": false },
+        { "label": "Restart and Install Update", "command": "application:install-update", "visible": false},
+        { "label": "Check for Update", "command": "application:check-for-update", "visible": false},
+        { "label": "Downloading Update", "enabled": false, "visible": false},
+        { "type": "separator" },
+        { "label": "Nylas N1 Help", "command": "application:view-help" }
+      ]
+    },
+    { "type": "separator" },
+    { "label": "Preferences", "command": "application:open-preferences" },
+    { "label": "Change Theme...", "command": "window:launch-theme-picker" },
+    { "label": "Install Theme...", "command": "application:install-package" },
+    { "type": "separator" },
+    { "label": "Print Current Thread", "command": "core:print-thread" },
+    { "type": "separator" },
+    { "label": "E&xit", "command": "application:quit" }
+  ]
+}
diff --git a/src/menu-manager.coffee b/src/menu-manager.coffee
index fe0b7ef2d..4ee3e4172 100644
--- a/src/menu-manager.coffee
+++ b/src/menu-manager.coffee
@@ -1,7 +1,6 @@
 path = require 'path'
 
 _ = require 'underscore'
-CSON = require 'season'
 fs = require 'fs-plus'
 {ipcRenderer} = require 'electron'
 {Disposable} = require 'event-kit'
diff --git a/src/package.coffee b/src/package.coffee
index b4d6a1668..74e265356 100644
--- a/src/package.coffee
+++ b/src/package.coffee
@@ -20,7 +20,7 @@ catch error
   packagesCache = {}
 
 # Loads and activates a package's main module and resources such as
-# stylesheets, keymaps, grammar, editor properties, and menus.
+# stylesheets, keymaps, and menus.
 module.exports =
 class Package
   EmitterMixin.includeInto(this)
@@ -45,10 +45,6 @@ class Package
     metadata ?= {}
     metadata.name = packageName
 
-    if metadata.stylesheetMain?
-      deprecate("Use the `mainStyleSheet` key instead of `stylesheetMain` in the `package.json` of `#{packageName}`", {packageName})
-      metadata.mainStyleSheet = metadata.stylesheetMain
-
     if metadata.stylesheets?
       deprecate("Use the `styleSheets` key instead of `stylesheets` in the `package.json` of `#{packageName}`", {packageName})
       metadata.styleSheets = metadata.stylesheets
@@ -250,9 +246,9 @@ class Package
   getKeymapPaths: ->
     keymapsDirPath = path.join(@path, 'keymaps')
     if @metadata.keymaps
-      @metadata.keymaps.map (name) -> fs.resolve(keymapsDirPath, name, ['json', 'cson', ''])
+      @metadata.keymaps.map (name) -> fs.resolve(keymapsDirPath, name, ['json', ''])
     else
-      fs.listSync(keymapsDirPath, ['cson', 'json'])
+      fs.listSync(keymapsDirPath, ['json'])
 
   getMenuPaths: ->
     menusDirPath = path.join(@path, 'menus')