Validators
Meta Tag Checker
Titles, descriptions, canonicals and robots directives
Meta tags are the smallest surface with the largest failure modes. A canonical pointing at the wrong URL removes a page from search. A stray `noindex` left over from staging does the same, silently, and nothing on the page looks different.
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This checks the tags search engines actually consume: title presence and length, meta description length, canonical correctness and self-reference, robots directives and their interaction, viewport, charset, and language declaration.
Length rules are guidance, not law - Google rewrites titles when it judges its own version more useful, and a description outside the range is a missed opportunity rather than an error. They are weighted accordingly, so the genuinely destructive problems stand out instead of competing with a title three characters too long.
Why this matters
You cannot see any of this in a browser
Meta tags render nothing. A page can look finished, load quickly and read well while it is quietly telling search engines to ignore it, or to credit a different URL. Nothing errors and nothing looks broken, so you find out weeks later — from a flat traffic graph, or from someone asking why the site is not coming up.
What it costs you when this is wrong
The page is removed from search
One robots meta tag containing noindex takes the page out of results entirely, while it carries on loading and converting for anyone who has the link. It normally surfaces weeks later as a question: why has this page never appeared?
Credit goes to a URL you did not choose
A canonical nominates the authoritative URL. Point it at the wrong page — easy when the tag is templated across a whole site — and search engines consolidate on that page instead; leave it relative and it resolves against the current URL, consolidating nothing while looking correct. The symptom is pages that get indexed and never rank.
A phone gets a shrunken desktop page
With no viewport meta tag a mobile browser assumes a desktop-width layout and scales the whole page down, so the text has to be pinched to be read. You rarely catch it yourself, because you are testing on a laptop; visitors just leave.
Why run it here
It ranks findings by what they cost
Every rule carries a severity and an importance from 1 to 10, and the report is ordered by it. A robots noindex is critical at 10; a description over 160 characters is a warning at 5; the eleven informational tags in this check — theme colour, generator, author and the rest — are reported but kept out of the score entirely, so a missing nicety never competes with a real defect.
It reads the page after the scripts run
A real browser loads the page first, and the tags are judged against the rendered head rather than the raw response. A canonical or robots directive injected by a tag manager or a plugin is therefore seen, and the untouched server response is kept separately for markup conformance.
Any URL, no account, nothing kept
There is no sign-in and no ownership check, so you can audit a client's site, a competitor's, or one you are about to inherit. The full report is held for about an hour and then gone — only the score and the date remain.
This check runs on its own here, and as part of the full audit alongside the other 985 rules. Either way the findings carry their evidence and their citation, and the report is never published or kept.
How to fix meta tags
Meta tags are what a search result is assembled from. Every duplicate is a page competing with another of your own.
Write a unique title per page, under about 60 characters, leading with the distinguishing term.
Write a unique meta description per page, around 150 characters, as the sentence you would want shown rather than a keyword list.
Add a self-referencing canonical to every indexable page.
Include the viewport meta tag, without which a mobile browser renders your page at desktop width and zooms out.
Check that no robots meta tag is accidentally set to noindex — the most expensive single line a site can ship by accident.
What happens when you run it
Enter your address
Just the domain is enough — example.com, with or without the https. No account, no card, no crawl of your whole site.
We render it like a visitor
Your page opens in a real browser and JavaScript runs to completion, so what gets audited is the page a person actually sees — not the raw HTML your server sent. A screenshot comes back with the report as evidence of exactly what we measured.
You get findings you can act on
Up to 986 checks run against that rendered page. Each finding names the rule, quotes the evidence found on your page, cites the public specification behind it, and says what to change. Nothing is a judgement call — run it twice on an unchanged page and the score is identical.
What runs this check
- Real browser rendering
- HTML Living Standard
Named because provenance is the product. Every finding in your report says which of these produced it, so you can check the reasoning rather than take a score on faith.
What this checks
24 rules · 13 affect your scoreA noindex robots meta tag removes the page from search results entirely. When unintentional this single tag outweighs every other SEO signal on the page.
SEO_ROBOTS_META_INDEXABLE scoredTitle tag exists
CriticalEvery indexable page must have a non-empty <title> element.
SEO_TITLE_EXISTS scoredTitles significantly longer than ~60 characters are commonly truncated in search results.
SEO_TITLE_LENGTH scoredCanonical URL declared
MediumA rel=canonical link tells search engines which URL is authoritative, preventing duplicate-content dilution across parameterised or syndicated copies of a page.
SEO_CANONICAL_EXISTS scoredA title is required by the HTML specification, not merely recommended, and every validator reports its absence as an error.
HTML_HEAD_HAS_TITLE scoredWithout a viewport meta tag mobile browsers render at a 980px virtual width and scale down, so the page arrives zoomed out and unreadable regardless of how good the responsive CSS is.
HTML_META_VIEWPORT_PRESENT scoredMeta description present
MediumWithout a meta description search engines synthesise a snippet from page text, which is usually a worse advert for the page than one written deliberately.
SEO_META_DESCRIPTION_EXISTS scoredThe lang attribute drives hyphenation, speech synthesis and correct font selection.
HTML_LANG_ATTRIBUTE scoredWithout a declared encoding the browser guesses, and a wrong guess renders every non-ASCII character as mojibake. The declaration must also appear in the first 1024 bytes, which is why it belongs at the top of head.
HTML_META_CHARSET_FIRST scoredA relative canonical is resolved against the current page, so it silently self-canonicalises rather than consolidating anything.
SEO_CANONICAL_ABSOLUTE scoredMeta descriptions outside roughly 50-160 characters are often rewritten or truncated by search engines.
SEO_META_DESCRIPTION_LENGTH scoredTitle is not too short
MediumA three-word title wastes the highest-value text on the page and rarely matches how anyone searches.
SEO_TITLE_MIN_LENGTH scoredA very short description leaves most of the available snippet space unused.
SEO_META_DESC_MIN_LENGTH scoredPage author meta is a supplementary signal browsers and platforms may use. Informational.
SEO_META_AUTHOR detectionReferrer policy meta is a supplementary signal browsers and platforms may use. Informational.
SEO_META_REFERRER detectionmax-image-preview:large is required for large image thumbnails in Discover and results.
SEO_ROBOTS_MAX_IMAGE detectionA crawlable language switcher helps search engines discover localised versions.
SEO_LANGUAGE_SWITCHER detectioniOS web app title is a supplementary signal browsers and platforms may use. Informational.
SEO_META_APPLE_MOBILE_WEB_APP_TITLE detectionApplication name is a supplementary signal browsers and platforms may use. Informational.
SEO_META_APPLICATION_NAME detectionFormat detection is a supplementary signal browsers and platforms may use. Informational.
SEO_META_FORMAT_DETECTION detectionGenerator meta is a supplementary signal browsers and platforms may use. Informational.
SEO_META_GENERATOR detectionContent rating is a supplementary signal browsers and platforms may use. Informational.
SEO_META_RATING detectionBrowser theme colour is a supplementary signal browsers and platforms may use. Informational.
SEO_META_THEME_COLOR detectionmax-snippet controls how much text search engines may show, which matters for paywalled and licensed content.
SEO_ROBOTS_MAX_SNIPPET detection
Questions
- Does meta description affect ranking?
- Not directly - it has not been a ranking factor for years. It affects click-through, because it is often the snippet. Google replaces it with page text whenever it thinks that serves the query better, which is most of the time for long-tail queries.
- What is the right title length?
- Around 50-60 characters is the usual guidance, but the real limit is pixel width, not characters, and Google truncates or rewrites as it sees fit. Treat the range as a signal that a title is drifting long, not as a rule.
Also checks
This page answers these searches too — they are the same job, so they share one page rather than being split across near-identical ones:
- meta description checker
- title tag checker
- meta tag analyzer
- seo meta checker
Other checkers
- HTML ValidatorW3C markup conformance, checked by a real parser
- CSS ValidatorStylesheets parsed and checked against the W3C property grammars
- Schema Markup ValidatorJSON-LD parsed, expanded to real schema.org IRIs, and checked
- Rich Results TestWhich search features your structured data qualifies for
- Website Scam DetectorThe trust signals people and payment processors check before believing a site
- AI ValidatorWhether AI models can find, read, quote and operate your site
- Broken Link CheckerEvery link on the page requested, with blocked and broken told apart
- SEO CheckerTitles, meta, canonicals, indexability and internal linking
- Accessibility CheckerTwo WCAG engines — one in a real browser, one on your markup
- Security Headers CheckerResponse headers, CSP quality, and the TLS certificate underneath
- Core Web Vitals CheckerMeasured for real, plus the page-weight causes behind the numbers
- AI Agent Readiness CheckerCan an agent find your buttons, read your labels and finish the task
- W3C ValidatorMarkup and stylesheet conformance in one pass
- Answer Engine CheckerWhether AI answer engines can quote you, and attribute it
- AI Crawler CheckerWhich AI crawlers your robots.txt actually lets in
- SSL Certificate CheckerA real handshake: certificate, expiry, protocol and cipher
- robots.txt CheckerWhat your robots.txt actually allows, group by group
- Open Graph CheckerHow your link looks when someone shares it
- Image SEO CheckerAlt text, dimensions, formats and lazy loading
- Mobile-Friendly TestViewport, tap targets and responsive behaviour
- Website CheckerEvery module, one scan, one prioritised fix list
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