Validators
HTML Validator
Check your HTML code for syntax errors, unclosed tags, and accessibility issues instantly. This tool provides real-time feedback with line-by-line diagnostics to help you build valid and SEO-friendly websites.
Check your HTML code for syntax errors, unclosed tags, and accessibility issues instantly. This tool provides real-time feedback with line-by-line diagnostics to help you build valid and SEO-friendly websites.
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Tip
Always include a DOCTYPE declaration at the start of your file to ensure the browser renders in standards mode.
Did You Know?
Invalid HTML can cause unexpected Layout Shifts, which negatively impacts your Google Search ranking and Core Web Vitals.
<div> or <span> is a frequent cause of broken layouts.<div> inside an inline <p> tag.id attribute multiple times on a single page, which breaks DOM selection and accessibility.alt attribute on <img> tags, which is a critical requirement for web accessibility standards.Best Practice
Use semantic elements like <nav> or <article> instead of generic <div> tags to improve SEO and screen reader support.
<header>, <footer>, and <main> over generic containers to provide meaningful structure.Q: Does this tool support HTML5? A: Yes, the validator is designed to check your code against the latest HTML5 standards and living specifications.
Q: Why is my layout broken if the HTML is valid? A: Validation checks syntax and structure. If your HTML is valid but the layout is wrong, the issue likely resides in your CSS or logic.
Q: Can I validate partial HTML snippets? A: Yes, you can paste either a complete document or just a fragment of code to check for specific syntax errors.
Tip
Self-closing tags like <img /> are optional in HTML5 but using them consistently can make your code easier to read.