Skip to content
✅

HTML Validator

Developer

Validate HTML markup and catch missing tags, deprecated elements, and accessibility issues.

0
0

Markup that renders fine in one browser can still be missing a closing tag, using an element deprecated a decade ago, or leaving out an alt attribute a screen reader actually depends on, none of which show up as a visible error since a browser quietly works around most broken markup instead of failing loudly. This tool validates HTML and flags a missing tag, a deprecated element, or an accessibility issue like a missing alt attribute, catching problems a browser silently tolerates rather than waiting for them to surface as an actual bug.

See more about the HTML Validator

Useful for catching a missing closing tag left over from an edit before it causes a rendering problem in a different browser, finding a deprecated element still lingering from an old redesign, or confirming images actually have alt text before a page ships to production.

Key features

  • Clean interface
  • Fast processing
  • No signup required
  • Works offline

Related Developer tools

JSON to TypeScript Types

Developer

User Agent Parser

Developer

Regex Pattern Builder

Developer

Hash Diff Checker

Developer

HTML Attribute Encoder

Developer

Random String Generator

Developer

Related Blog Posts

Quick answers for HTML Validator

What counts as a "missing tag" error?
It tracks opening and closing tags with a stack as it scans, and flags both unclosed tags left on the stack and closing tags that do not match the tag that was actually open.
Which deprecated tags does it flag?
Old presentational tags like <center>, <font>, <marquee>, <blink>, and <strike>, with a suggestion to use CSS instead.
What accessibility issues does it check for?
Missing alt attributes on <img> tags, plus javascript: URLs in href attributes, which are flagged as both a security and accessibility concern.