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W3C CSS Validation Service

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Statistics on css-validator

Number of watchers on Github 72
Number of open issues 20
Average time to close an issue 2 months
Main language CSS
Average time to merge a PR 3 days
Open pull requests 5+
Closed pull requests 7+
Last commit over 1 year ago
Repo Created about 4 years ago
Repo Last Updated over 1 year ago
Size 62.6 MB
Homepage https://jigsaw.w3...
Organization / Authorw3c
Latest Releasecssval-201801
Page Updated
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CSS Validator Project Jigsaw Powered

Build Status

The latest development code for the CSS Validator is available through the GitHub repository.

For a visual representation, see the CSS Validator Sequence Diagram, which is available in png, graffle and svg formats.

If you have any questions or problems with the validator, send us an email.

Download and compilation of the software do not give the right to use the W3C logo on the service. The use of the W3C logo on your site requires prior approval from the W3C Team (

css-validator open issues Ask a question     (View All Issues)
  • over 3 years Avoid casting in number -> unit checks
  • almost 4 years Can I run this locally just from the .jar?
  • almost 4 years Validator seems to process only one level of CSS 3 rules
  • about 4 years Move HTML documentation under /docs/
  • about 4 years Run autotests in Travis CI
  • about 4 years Add Ant task to compile autotest
  • about 4 years Add a couple options to squelch errors for certain CSS browser hacks
  • about 4 years Tag a release
  • about 4 years Setup GitHub Pages site for the documentation
css-validator open pull requests (View All Pulls)
  • Treat \9 legacy IE property hack as a vendor extension warning (mostly)
  • Master
  • Allow @supports and @viewport (without checking)
  • Allow CSS custom properties (without checking)
  • Report bad prop in declaration w/ vendor/hack flag
css-validator questions on Stackoverflow (View All Questions)
  • W3C CSS Validator not detecting correct syntax like WebStorm
  • Programmatically getting results of a W3C CSS Validator in Python
  • CSS Validator is saying my usage of text-wrap:suppress is invalid
  • Is there an open source CSS validator that can be run locally?
  • css validator showing parse errors
  • CSS Validator doesn't recognize flex-wrap: wrap;
  • W3 Css validator errors on -moz and -webkit
  • Difference between and CSS validators?
  • Differences between and css validator?
  • W3C CSS Validator error with required attribute
  • W3C CSS Validator - Parse error
  • w3c css validator parse error
  • Can I suppress the errors and warnings in a CSS file, shown by the CSS validator?
  • css validator error HTML5 Conformance Checker
  • The [semi-?] official CSS validator complains about some MS CSS
  • Adding a PHP expression warning exception in CSS validator
  • Is there a CSS validator that is not as strict as W3C's that will validate things like normalize.css?
  • Processing W3C css validator output with Violations
  • W3C CSS Validator result 'Value Error : font-family Property font-family doesn't exist in CSS level 2.1 but exists in [css1, css2, css3] : Helvetica'
  • CSS Validator library for Java
  • CSS Validator at media syntax
  • CSS validator where you can disable error messages on per file basis
  • How can W3C CSS Validator identify a css3 document?
  • Is there a HTML and CSS validator which also checks for ie7 compatibility?
  • Css validator throwing up error on box shadow
  • w3c css validator doesn't validate CSS served by Liferay 6.0.6?
  • Parse Error [empty string] - W3C CSS Validator bug due to CSS size?
  • is there any css validator with CSS3 and vendor specific extensions support?
  • Why W3C CSS Validator showing parsing error on "Ends-with" Attribute Value Selector
  • CSS Validator - Ruby
css-validator list of languages used
css-validator latest release notes
cssval-201801 cssval-201801

Support for ignoring some CSS Hacks, as well as updates for properties.


Landed support for attr() (CSS3) and calc().

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