The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.


WebService::Validator::CSS::W3C - Interface to the W3C CSS Validator


  use WebService::Validator::CSS::W3C;

  my $css = "p { color: not-a-color }";
  my $val = WebService::Validator::CSS::W3C->new;
  my $ok = $val->validate(string => $css);

  if ($ok and !$val->is_valid) {
      print "Errors:\n";
      printf "  * %s\n", $_->{message}
        foreach $val->errors


This module is an interface to the W3C CSS Validation online service, based on its SOAP 1.2 support. It helps to find errors in Cascading Style Sheets.

The following methods are available:

my $val = WebService::Validator::CSS::W3C->new
my $val = WebService::Validator::CSS::W3C->new($ua)
my $val = WebService::Validator::CSS::W3C->new($ua, $url)

Creates a new WebService::Validator::CSS::W3C object. A custom LWP::UserAgent object can be supplied which is then used for HTTP communication with the CSS Validator. $url is the URL of the CSS Validator, by default.

my $success = $val->validate(%params)

Validate a style sheet, takes %params as defined below. Either string or uri must be supplied. Returns a true value if the validation succeeded (regardless of whether the style sheet contains errors).

string => $css

A style sheet as a string. It is currently unlikely that validation will work if the string is not a legal UTF-8 string. If a string is specified, the uri parameter will be ignored. Note that GET will be used to pass the string to the Validator, it might not work with overly long strings.

uri => $uri

The location of a style sheet or a HTML/XHTML/SVG document containing or referencing style sheets.

medium => "print"

The medium for which the style sheet should apply, one of aural, braille, embossed, handheld, print, screen, tty, tv, and presentation. A special value all can also be specified. The default is undef in which case the CSS Validator determines a value; this would currently be as if all had been specified.

profile => "css3"

The CSS Version or profile to validate against, legal values are css1, css2, css21, css3, svg, svgbasic, svgtiny, mobile, atsc-tv, and tv. A special value none can also be used. The default is undef in which case the CSS Validator determines a default.

warnings => 2

Either "no" or an integer 0 - 2 that determines how many warning messages you want to get back from the CSS Validator. "no" means no warning, 0 means only the most serious warnings, and 2 will give all warnings, including low level ones. The defaut is undef in which case the CSS Validator determines a default value; this is expected to be as if 1 had been specified.

language => "de"

The desired language of the supposedly human-readable messages. The string will passed as an Accept-Language header in the HTTP request. The CSS Validator currently supports en, de, fr, ja, nl, zh, and zh-cn.

my $success = $val->success

Same as the return value of validate().

my $is_valid = $val->is_valid

Returns a true value if the last attempt to validate() succeeded and the validator reported no errors in the style sheet.

my $num_errors = $val->errorcount

returns the number of errors found for the checked style sheet. Get the details of the errors with $val->errors (see below).

my @errors = $val->errors

Returns a list with information about the errors found for the style sheet. An error is a hash reference; the example in the synopsis would currently return something like

  ( {
    context    => 'p',
    property   => 'color',
    expression => { start => '', end => 'not-a-color' }
    errortype  => 'parse-error',
    message    => 'not-a-color is not a color value',
    line       => 0,
  } )
my $num_warnings = $val->warningcount

returns the number of warnings found for the checked style sheet. Get the details of each warning with $val->warnings (see below).

my @warnings = $val->warnings

Returns a list with information about the warnings found for the style sheet.

my $ua = $val->user_agent
my $ua = $val->user_agent($new_ua)

The LWP::UserAgent object you supplied to the constructor or a custom object created at construction time you can manipulate.

  # set timeout to 30 seconds

You can also supply a new object to replace the old one.

my $uri = $val->validator_uri
my $uri = $val->validator_uri($validator_uri)

Gets or sets the URI of the validator. If you did not specify a custom URI, by default.

my $response = $val->response

The HTTP::Response object returned from the last request. This is useful to determine why validation might have failed.

  if (!$val->validate(string => $css)) {
    if (!$val->response->is_success) {
      print $val->response->message, "\n"
my $uri = $val->request_uri

The URI object used for the last request.

my $som = $val->som

The SOAP::SOM object for the last successful deserialization, check the return value of validate() or success() before using the object.


This module uses the SOAP interface for the W3C CSS validatom, which still has a number of bugs, tracked via W3C's Bugzilla,

Please report bugs in the W3C CSS Validator to or enter them directly in Bugzilla (see above). Please report bugs in this module via RT,


This module is not directly associated with the W3C. Please remember that the CSS Validator is a shared resource so do not abuse it: you should sleep between requests, and consider installing the Validator locally, see


  Copyright 2004-2013 Bjoern Hoehrmann <>.
  This module is licensed under the same terms as Perl itself.