diff --git a/Library/Homebrew/cask/cask.rb b/Library/Homebrew/cask/cask.rb
index 02703f440b..372eba7077 100644
--- a/Library/Homebrew/cask/cask.rb
+++ b/Library/Homebrew/cask/cask.rb
@@ -19,7 +19,7 @@ module Cask
     extend Searchable
     include Metadata
 
-    attr_reader :token, :sourcefile_path, :source, :config, :default_config
+    attr_reader :token, :sourcefile_path, :source, :config, :default_config, :loaded_from_api
 
     attr_accessor :download, :allow_reassignment
 
@@ -44,12 +44,14 @@ module Cask
       @tap
     end
 
-    def initialize(token, sourcefile_path: nil, source: nil, tap: nil, config: nil, allow_reassignment: false, &block)
+    def initialize(token, sourcefile_path: nil, source: nil, tap: nil, config: nil,
+                   allow_reassignment: false, loaded_from_api: false, &block)
       @token = token
       @sourcefile_path = sourcefile_path
       @source = source
       @tap = tap
       @allow_reassignment = allow_reassignment
+      @loaded_from_api = loaded_from_api
       @block = block
 
       @default_config = config || Config.new
@@ -133,7 +135,10 @@ module Cask
 
     def installed_caskfile
       installed_version = timestamped_versions.last
-      metadata_main_container_path.join(*installed_version, "Casks", "#{token}.rb")
+      caskfile_dir = metadata_main_container_path.join(*installed_version, "Casks")
+      return caskfile_dir.join("#{token}.json") if caskfile_dir.join("#{token}.json").exist?
+
+      caskfile_dir.join("#{token}.rb")
     end
 
     def config_path
diff --git a/Library/Homebrew/cask/cask_loader.rb b/Library/Homebrew/cask/cask_loader.rb
index 1b21258758..7b5b5d8774 100644
--- a/Library/Homebrew/cask/cask_loader.rb
+++ b/Library/Homebrew/cask/cask_loader.rb
@@ -51,7 +51,7 @@ module Cask
     class FromPathLoader < FromContentLoader
       def self.can_load?(ref)
         path = Pathname(ref)
-        path.extname == ".rb" && path.expand_path.exist?
+        %w[.rb .json].include?(path.extname) && path.expand_path.exist?
       end
 
       attr_reader :token, :path
@@ -59,7 +59,7 @@ module Cask
       def initialize(path) # rubocop:disable Lint/MissingSuper
         path = Pathname(path).expand_path
 
-        @token = path.basename(".rb").to_s
+        @token = path.basename(path.extname).to_s
         @path = path
       end
 
@@ -71,6 +71,10 @@ module Cask
         @content = path.read(encoding: "UTF-8")
         @config = config
 
+        if path.extname == ".json"
+          return FromAPILoader.new(token, from_json: JSON.parse(@content)).load(config: config)
+        end
+
         begin
           instance_eval(content, path).tap do |cask|
             raise CaskUnreadableError.new(token, "'#{path}' does not contain a cask.") unless cask.is_a?(Cask)
@@ -201,13 +205,15 @@ module Cask
         Homebrew::API::Cask.all_casks.key?(token)
       end
 
-      def initialize(token)
+      def initialize(token, from_json: nil)
         @token = token.delete_prefix("homebrew/cask/")
         @path = CaskLoader.default_path(token)
+        @from_json = from_json
       end
 
       def load(config:)
-        json_cask = Homebrew::API::Cask.all_casks[token]
+        json_cask = @from_json || Homebrew::API::Cask.all_casks[token]
+        cask_source = JSON.pretty_generate(json_cask)
 
         if (bottle_tag = ::Utils::Bottles.tag.to_s.presence) &&
            (variations = json_cask["variations"].presence) &&
@@ -230,7 +236,7 @@ module Cask
 
         tap = Tap.fetch(json_cask[:tap]) if json_cask[:tap].to_s.include?("/")
 
-        Cask.new(token, tap: tap, source: cask_source, config: config) do
+        Cask.new(token, tap: tap, source: cask_source, config: config, loaded_from_api: true) do
           version json_cask[:version]
 
           if json_cask[:sha256] == "no_check"
diff --git a/Library/Homebrew/cask/installer.rb b/Library/Homebrew/cask/installer.rb
index 6f5c8d09e8..9075bb651a 100644
--- a/Library/Homebrew/cask/installer.rb
+++ b/Library/Homebrew/cask/installer.rb
@@ -386,7 +386,8 @@ module Cask
 
       return if @cask.source.blank?
 
-      (metadata_subdir/"#{@cask.token}.rb").write @cask.source
+      extension = @cask.loaded_from_api ? "json" : "rb"
+      (metadata_subdir/"#{@cask.token}.#{extension}").write @cask.source
       old_savedir&.rmtree
     end