HTML Validator — W3C-style HTML Linting & Formatting

Validate your HTML structure and formatting instantly. This tool checks for common errors, accessibility issues, and formatting mistakes using W3C-style rules — in-browser and free.

HTML Validator (W3C-style)
Paste your HTML code
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Instant HTML Validation

Paste your HTML and press "Format & Validate" to see issues highlighted immediately. This tool helps you find syntax errors, invalid nesting, missing attributes, and other common HTML mistakes — without leaving your browser.

Why Validate Your HTML?

  • 🔍 Improve accessibility with correct ALT and semantic tags
  • 🧩 Fix structural bugs in templates and components
  • 📄 Clean up auto-generated HTML from design tools
  • 📈 Boost SEO by maintaining well-formed markup
  • ⚡ Avoid rendering inconsistencies across browsers

Rules Checked (Sample)

  • ❌ Missing DOCTYPE
  • ❌ Duplicate IDs
  • ❌ Empty src attributes
  • ❌ Missing alt text on images
  • ❌ Tag case errors (<Div> instead of <div>)
  • ❌ Improper self-closing or missing tag pairs

Who Should Use This Tool?

  • 🧑‍💻 Web developers writing raw HTML
  • 📩 Email template creators
  • 🎨 Designers exporting HTML from builders
  • 🧪 QA testers checking rendering safety
  • 📚 Students learning HTML fundamentals

How to Use

  1. Paste or write your HTML into the editor
  2. Click “Format & Validate”
  3. See results line by line with issues highlighted
  4. Fix the errors based on feedback shown

Why ToolMateX HTML Validator?

  • 🚀 Fast & responsive linting
  • 📐 Auto-formats before validation
  • 🔐 Private — runs entirely in your browser
  • 🧠 Educational — errors explained line-by-line
  • 🆓 Free to use forever

Frequently Asked Questions (FAQs)

Why Use ToolMateX

Tired of bloated tool websites with 10 ads per click? This platform is built for speed, simplicity, and reliability. Whether you're debugging JSON or testing colors, we’ve got your back.

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Free to Use, Forever

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