HTML Validator & Compliance Checker
Every place your markup isn't strictly 100% to the HTML Living Standard, with the exact example and the correction.
0
Strict errors
0
Obsolete / deprecated
2
Style / non-minimal
52
Total occurrences
ERROR
Strict errors: the W3C Nu validator would reject these. Missing required attributes, duplicate IDs, self-closed non-void elements, unsupported DOCTYPEs.
OBSOLETE
Deprecated per HTML Living Standard §15. Browsers still render them but conforming validators flag them.
STYLE
Valid but non-minimal: uppercase tags, XHTML-style
<br />, redundant type="text/javascript". Legal HTML5, but not what the spec writes.
Syntax
STYLE
Uppercase or mixed-case attribute name
26 × on this pageValid HTML5, but inconsistent with the spec's recommended minimal form. · Rule: SYN_UPPERCASE_ATTR
HTML is case-insensitive for attributes but the spec, browsers' own DOM serialisation, and every popular linter normalise to lowercase.
Fix: Write attribute names in lowercase.
✗ Example from this page
<meta … charSet="…">
✓ Correct form
charset="…"
All 26 occurrences
L1
<meta … charSet="…">
L1
<link … fetchPriority="…">
L1
<link … hrefLang="…">
L1
<link … hrefLang="…">
L1
<link … hrefLang="…">
L1
<link … hrefLang="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
L310
<svg … viewBox="…">
–
… (additional occurrences omitted)
STYLE
XHTML-style trailing slash on void element
26 × on this pageValid HTML5, but inconsistent with the spec's recommended minimal form. · Rule: SYN_VOID_TRAILING_SLASH
<br/> and <img … /> are legal HTML5, but the / is completely ignored by the parser. It's a leftover from XHTML and the HTML spec explicitly notes it has no effect. Drop it for minimal, idiomatic HTML5.
Fix: Write the void element without the trailing slash: <meta>.
✗ Example from this page
<meta charSet="utf-8"/>
✓ Correct form
<meta>
All 26 occurrences
L1
<meta charSet="utf-8"/>
L1
<meta name="viewport" content="width=device-width, initial-scale=1"/>
L1
<link rel="preload" href="/logo.webp" as="image"/>
L1
<link rel="preload" href="/videos/hero/hero-still.webp" as="image"/>
L1
<link rel="preload" as="image" href="/imgs/musicvideoai/three-tools/tool-agent.webp"/>
L1
<link rel="preload" as="image" href="/imgs/musicvideoai/three-tools/tool-workflow.webp"/>
L1
<link rel="preload" as="image" href="/imgs/musicvideoai/three-tools/tool-editor.webp"/>
L1
<link rel="preload" href="/imgs/musicvideoai/1.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/how-to-use/2.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/how-to-use/3.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/no-track/01.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/no-track/02.webp" as="image"/>
L1
<link rel="stylesheet" href="/assets/index-A_OIlJLU.css" data-rsc-css-href="/assets/index-A_OIlJLU.css" data-precedence="vite-rsc/importer-resources"/>
L1
<link rel="modulepreload" fetchPriority="low" href="/assets/index-BH9YqUeN.js"/>
L1
<link rel="preload" href="/imgs/musicvideoai/no-track/03.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/no-track/04.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/features-pro/01.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/features-pro/02.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/features-pro/03.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/why/01.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/why/02.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/why/03.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/why/04.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/stills/hero-video-new-agent.webp" as="image"/>
L1
<link rel="preload" href="/imgs/musicvideoai/hero-new-icon/google.webp" as="image"/>
–
… (additional occurrences omitted)