Index: t/validators/yaml.t
===================================================================
--- t/validators/yaml.t	(revision 0)
+++ t/validators/yaml.t	(revision 0)
@@ -0,0 +1,50 @@
+use strict;
+use warnings;
+
+use Test::More tests => 8;
+
+use HTML::FormFu;
+
+BEGIN { use_ok('YAML'); }
+
+my $form = HTML::FormFu->new;
+
+$form->element('Text')->name('foo')->validator('YAML');
+$form->element('Text')->name('bar')->validator('YAML');
+
+# Valid
+{
+    $form->process( {
+            foo => "---\ntest:\n  - list1: [ item ]\n",
+            bar => "thing: yes\nstuff: no\n",
+        } );
+
+    ok( $form->valid('foo'), 'foo valid' );
+    ok( $form->valid('bar'), 'bar valid' );
+}
+
+# Invalid
+{
+    my $invalid = 'aaa';
+
+    $form->process( {
+            foo => $invalid,
+            bar => 'foo\n-',
+        } );
+
+    ok( !$form->valid('foo'), 'foo not valid' );
+    ok( !$form->valid('bar'), 'bar not valid' );
+
+    my ($error) = @{ $form->get_errors };
+
+    my $error_msg = 'Invalid YAML';
+    eval { YAML::Load($invalid) };
+
+    if ($@) {
+        ($error_msg) = ($@ =~ /^(.*?)\n/);
+    }
+
+    is( $error->class,   'error_validator_yaml' );
+    is( $error->type,    'YAML' );
+    like( $error->message, qr/^${error_msg}/ );
+}
Index: lib/HTML/FormFu/I18N/en.pm
===================================================================
--- lib/HTML/FormFu/I18N/en.pm	(revision 1009)
+++ lib/HTML/FormFu/I18N/en.pm	(working copy)
@@ -30,6 +30,8 @@
     form_inflator_imager       => 'Error opening image file',
     form_validator_imager_size => 'Image upload too large',
     form_transformer_imager    => 'Error processing image file',
+
+    form_validator_yaml => 'Invalid YAML',
 );
 
 1;
Index: lib/HTML/FormFu/Validator/YAML.pm
===================================================================
--- lib/HTML/FormFu/Validator/YAML.pm	(revision 0)
+++ lib/HTML/FormFu/Validator/YAML.pm	(revision 0)
@@ -0,0 +1,70 @@
+package HTML::FormFu::Validator::YAML;
+
+use strict;
+use base 'HTML::FormFu::Validator';
+
+use YAML qw(Load);
+
+sub validate_value {
+    my ( $self, $value ) = @_;
+
+    my $ok = 1;
+
+    eval { my $data = Load($value) };
+
+    if ($@) {
+        # Capture first line of stack trace because that's where the error
+        # message is
+        my ($msg) = ($@ =~ /^(.*?)\n/);
+        if ($msg) {
+            # build validator exception
+            my $exception = HTML::FormFu::Exception::Validator->new;
+            $exception->message("$msg");
+            die $exception;
+        } else {
+            # We couldn't extract an error message from the stack trace, so
+            # use default i18n error message instead
+            $ok = 0;
+        }
+    }
+
+    return $ok;
+}
+
+1;
+
+__END__
+
+=head1 NAME
+
+HTML::FormFu::Validator::YAML - YAML validator
+
+=head1 SYNOPSIS
+
+    $field->validator('YAML');
+
+    ---
+    elements:
+      - type: Text
+        name: foo
+        validators:
+          - type: YAML
+
+=head1 DESCRIPTION
+
+YAML validator.
+
+=head1 SEE ALSO
+
+Is a sub-class of, and inherits methods from L<HTML::FormFu::Validator>
+
+L<HTML::FormFu::FormFu>
+
+=head1 AUTHOR
+
+Byron Young C<youngb@riverbed.com>
+
+=head1 LICENSE
+
+This library is free software, you can redistribute it and/or modify it under
+the same terms as Perl itself.