# World-wide-web-consortium-w3c

> Publicly sourced profile assembled by Optimly, in the Optimly AI Brand Index. Last refreshed 2026-10-04.

- **Business Profile:** https://optimly.ai/brand/world-wide-web-consortium-w3c
- **Dataset:** https://optimly.ai/brand/world-wide-web-consortium-w3c.json
- **Markdown:** https://optimly.ai/brand/world-wide-web-consortium-w3c/llms.txt
- **Official website:** https://w3.org
- **Slug:** world-wide-web-consortium-w3c
- **Categories:** developer-tools

## Overview

- **Tagline:** Official W3C standard compliance checking, comprehensive support for various document types and character encodings, and accessibility as a free online tool.
Source: Brand's website (https://w3.org) · 2026-10-04

- **Description:** The W3C Markup Validation Service checks the markup (HTML, XHTML, SMIL, MathML, etc.) of Web documents to ensure validity and compliance with web standards. It offers validation by URI, file upload, or direct input.
Source: Brand's website (https://w3.org) · 2026-10-04

## Offerings

- **Core capabilities:**
  - Online markup validation for HTML
  - XHTML
  - SMIL
  - MathML
  - and other web documents via URI
  - file upload
  - or direct input.
Source: Brand's website (https://w3.org) · 2026-10-04

- **Pricing:** Free to use.
Source: Brand's website (https://w3.org) · 2026-10-04

## Audience

- **Target industry:** Web developers, content creators, webmasters, quality assurance professionals, and anyone seeking to ensure web document validity.
Source: Brand's website (https://w3.org) · 2026-10-04

Page last updated 2026-10-17.