HTML & CSS W3C Validator Pro

Name: HTML & CSS W3C Validator Pro
Rating: 5 (4 reviews)
Author: Rocco Caruso

Advanced validator that extracts, merges, and validates HTML/CSS (including external styles) via W3C standards.

As of June 2026, HTML & CSS W3C Validator Pro has 110 users and a 5.00/5 rating from 4 reviews in the Developer Tools category.

Rocco Caruso Developer Tools

Chrome Web Store ↗.crx

Users+86.4%

110

Rating0%

5.00

4 reviews

Reviews0%

Version

1.4

Manifest V3

History

9 snapshots

Tracking since Apr 1, 2026.

View as table

Date	Users	Rating	Reviews	Version
Apr 1, 2026	59	5.00	4	1.4
Apr 16, 2026	60	5.00	4	1.4
Apr 22, 2026	67	5.00	4	1.4
Apr 27, 2026	78	5.00	4	1.4
May 4, 2026	79	5.00	4	1.4
May 10, 2026	81	5.00	4	1.4
May 18, 2026	92	5.00	4	1.4
May 27, 2026	100	5.00	4	1.4
Jun 5, 2026	101	5.00	4	1.4
Now	110	5.00	4	1.4

Permissions & access

Permissions: activeTabscripting
Host access: https://validator.w3.org/*, https://jigsaw.w3.org/*, <all_urls>

Screenshots

HTML & CSS W3C Validator Pro screenshot 1

HTML & CSS W3C Validator Pro screenshot 2

HTML & CSS W3C Validator Pro screenshot 3

About

HTML & CSS W3C Validator Pro
Ensure your code meets World Wide Web Consortium (W3C) standards with a single click.

Developing clean, standards-compliant websites is essential for SEO, accessibility, and cross-browser compatibility. This extension streamlines the debugging process by sending your page's code directly to the official W3C Validators, eliminating the need for manual copy-pasting.

Unlike basic tools, this extension is built for the modern web: it handles dynamic DOM states, external frameworks, and complex stylesheets effortlessly.

🚀 KEY FEATURES
Advanced HTML5 Validation: Captures the current state of your DOM, including elements generated dynamically by JavaScript.
Smart CSS Validation (Pro): Overcomes CORS restrictions to analyze stylesheets that standard validators often miss.
Merge & Validate: Automatically fetches all internal and external styles (including CDNs like Bootstrap or Tailwind), merging them into a single block for a complete audit.
Used CSS Analysis: Focus on efficiency by extracting and validating only the rules currently affecting elements on your page.
Source Validation: Ideal for checking raw .css files or the direct page source in the browser.

👨‍💻 DEVELOPER-CENTRIC WORKFLOW
Official Standards: Direct integration with validator.w3.org and jigsaw.w3.org.
Visual Feedback: Provides immediate status indications and cursor updates while processing complex data.
Privacy-Focused: Built on Manifest V3 with no tracking or ads; your code is only sent to W3C servers for analysis.
Secure Execution: Utilizes safe fetching methods to protect user privacy while retrieving external assets.

🎯 IDEAL FOR
Web Developers: Identify unclosed tags, invalid attributes, and CSS syntax errors during production.
SEO Specialists: Ensure semantic markup is valid to improve search engine crawling.
Accessibility Experts: Verify code structure to maintain compatibility with screen readers.
QA Testers: Streamline technical audits for complex, framework-heavy applications.

Start writing higher-quality code today. Install HTML & CSS W3C Validator Pro.