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Validate HTML Tag Nesting with Confidence

A web-based tool to validate and verify HTML tag nesting according to W3C standards. Perfect for learning and ensuring your HTML code is clean and error-free.

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<div> → <p>

Valid nesting

<p> → <div>

Invalid nesting

<a> → <button>

Check details

Quick Start

Get started with HTML Tags Checker in three simple steps

1

Open the Tool

Visit the HTML Tags Checker by opening index.html in your web browser. No installation or setup required — it runs entirely in your browser.
# Clone the repository
git clone https://github.com/DanielVillalbaD/HTML-tags-checker.git
cd HTML-tags-checker

# Open index.html in your browser
open index.html
2

Enter Tags to Validate

Type the parent tag in the first input field and the child tag in the second input field. Then click Validate to check if the nesting is valid.
Tag names are case-insensitive. You can enter div, DIV, or Div — they all work the same.
3

Review the Results

The tool will display whether the nesting is valid, invalid, or allowed with a warning. You’ll also see a detailed explanation and a code example.
When you validate <div> containing <p>, you’ll see:
  • ✓ Allowed — The <div> tag is a block element and can contain block or inline elements like <p>.
  • A code example showing proper usage
  • Links to the nesting rules reference for more details

Key Features

Everything you need to validate HTML tag nesting

W3C Standards

Validates tag nesting according to official W3C HTML5 standards and specifications.

Bilingual Support

Full interface in both Spanish and English with instant language switching.

Real-time Validation

Instant feedback with detailed explanations and code examples for every validation.

Comprehensive Reference

Complete guide to HTML5 element categories and nesting rules with examples.

URL Parameters

Share validations using URL parameters for easy collaboration and documentation.

Accessible Design

Built with ARIA labels and keyboard navigation for full accessibility support.

Explore the Documentation

Learn how to use and integrate HTML Tags Checker

Core Concepts

Understand HTML nesting rules, element categories, and validation logic.

Learn more

Usage Guide

Learn how to validate tags, switch languages, and explore common examples.

Get started

Reference

Complete reference for supported elements, nesting rules, and best practices.

View reference

Developer Guide

Integrate the tool into your workflow and contribute to the project.

Explore

Ready to Validate Your HTML?

Start using HTML Tags Checker today to ensure your HTML is clean, valid, and follows W3C standards.

Get StartedView on GitHub