Index: app/controllers/custom_fields_controller.rb
===================================================================
--- app/controllers/custom_fields_controller.rb	(revision 11718)
+++ app/controllers/custom_fields_controller.rb	(working copy)
@@ -21,10 +21,16 @@
   before_filter :require_admin
   before_filter :build_new_custom_field, :only => [:new, :create]
   before_filter :find_custom_field, :only => [:edit, :update, :destroy]
+  accept_api_auth :index
 
   def index
     @custom_fields_by_type = CustomField.all.group_by {|f| f.class.name }
     @tab = params[:tab] || 'IssueCustomField'
+
+    respond_to do |format|
+      format.html { render :layout => 'base' }
+      format.api { @count = CustomField.all.count }
+    end
   end
 
   def new
Index: app/views/custom_fields/index.api.rsb
===================================================================
--- app/views/custom_fields/index.api.rsb	(revision 0)
+++ app/views/custom_fields/index.api.rsb	(revision 0)
@@ -0,0 +1,21 @@
+api.array :custom_fields, api_meta(:total_count => @count, :offset => 0, :limit => @count) do
+  @custom_fields_by_type.each do |type, fields|
+    fields.each do |field|
+      api.custom_field do
+        api.id                field.id
+        api.name              field.name
+        api.type              type
+        api.format            field.field_format
+        api.required          field.is_required?
+        api.searchable        field.searchable
+        api.multiple_values   field.multiple?
+        api.array :possible_values do
+          field.possible_values.each do |v|
+            api.value v
+          end
+        end
+        api.default_value    field.default_value
+      end
+    end
+  end
+end