string literals; why not.

app/views/accounts/_account.json.jbuilder

@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 json.extract! account, :id, :username, :password, :home, :site, :created_at, :updated_at
 json.url account_url(account, format: :json)

app/views/accounts/index.json.jbuilder

@@ -1 +1,2 @@
+# frozen_string_literal: true
 json.array! @accounts, partial: 'accounts/account', as: :account

app/views/accounts/show.json.jbuilder

@@ -1 +1,2 @@
+# frozen_string_literal: true
 json.partial! "accounts/account", account: @account