What a website metadata checker actually does
A metadata checker sends an HTTP request to your URL, parses the HTML <head> section, and extracts every relevant meta tag. It looks for <title>, <meta name="description">, <meta property="og:...">, <meta name="twitter:...">, <link rel="canonical">, <link rel="icon">, <link rel="alternate" hreflang="...">, <meta name="viewport">, and any <script type="application/ld+json"> blocks. It displays each tag with the attribute name and content value in a structured report.
Then it goes one step further. It renders a SERP preview card using the title and meta description as they would appear in Google search on desktop and mobile. It renders a Twitter card preview using the twitter:title, twitter:description, and twitter:image tags. It renders a LinkedIn preview using Open Graph tags. And it shows a Slack unfurl preview, which uses OG tags by default but falls back to page title if OG is missing.
Two problems are invisible until you see the preview. The first is truncation-titles longer than 60 characters or meta descriptions longer than 160 characters get cut off in Google. The second is missing images. A page might have a title and description but no og:image, so the Twitter card appears text-only and looks broken. Previews catch both instantly.
How to use this website metadata checker
- Paste the page URL into Page URL. Use the canonical version if you know it-https, www if applicable, no UTM parameters.
- Pick a User-agent from the dropdown if you want to see how metadata differs for mobile users or Googlebot. Desktop Chrome is the default. Mobile Chrome and Googlebot are useful for testing mobile-first indexing or JavaScript-rendered metadata.
- Paste a second URL into Compare with if you want to see your metadata next to a competitor's or check consistency across language versions of the same page.
- Hit Check metadata. You get a table of extracted tags, warnings for missing or invalid tags, and four rendered preview cards-Google SERP, Twitter/X, LinkedIn, and Slack.
- Expand the Warnings section if any rows are flagged. We report missing og:image, truncated titles, viewport misconfigurations, invalid schema, and hreflang errors.
Try checking a blog post URL. If the page has no Open Graph image, you see a Google preview with title and description, but the Twitter and LinkedIn previews show broken image placeholders. Add an og:image tag pointing to a 1200x630 PNG, re-check, and the previews update to show the hero image.
Why rendered previews matter more than raw tags
A tag can be technically present and still fail in practice. A title with 80 characters passes validation but gets truncated in Google at 60, so the last 20 characters are invisible to searchers. An og:image URL can return 404, making the tag useless even though it exists. A twitter:card set to summary_large_image requires a 2:1 aspect ratio image, but if the image is square, Twitter falls back to the small summary card.
Three practical consequences.
Click-through rate. Truncated titles and missing images hurt CTR in search and social. A polished preview with a clear title, benefit-driven description, and striking image gets more clicks than a plain-text snippet. Testing before publishing lets you fix layout before traffic is lost.
Brand consistency. If your homepage has perfect metadata but product pages have no OG image or fall back to the site logo, the user experience is inconsistent. Bulk-checking templates reveals which page types need fixes.
Platform differences. Google reads the title tag and meta description. Twitter reads twitter:title and twitter:description, or falls back to OG tags. LinkedIn reads OG tags only. Slack reads OG tags and sometimes the favicon. One missing tag can break the preview on one platform but not others. Seeing all four previews at once shows the gaps.
Open Graph vs Twitter Card vs schema.org
Open Graph tags were invented by Facebook and are now used by LinkedIn, Slack, Discord, and most social platforms. The core tags are og:title, og:description, og:image, og:url, and og:type. Setting these controls how links look when shared.
Twitter Card tags-twitter:card, twitter:title, twitter:description, twitter:image-override OG tags on Twitter/X. If both are present, Twitter reads the Twitter tags first. If only OG tags are present, Twitter uses them. Most sites set OG tags and skip Twitter tags because the fallback works. The exception is twitter:card, which should be set to summary_large_image if you want the big-image preview.
Schema.org structured data lives in JSON-LD scripts in the <head> or <body>. It tells Google what type of content the page contains-Article, Product, Recipe, Event, FAQ-and provides machine-readable fields like author, publish date, price, and rating. Google uses this for rich results like star ratings in search. Our checker validates JSON-LD syntax and reports the schema types found.
Hreflang, canonical, and viewport
Hreflang tags declare language and regional variants of a page. If you have English, Spanish, and French versions of /about, each should have <link rel="alternate" hreflang="es" href="..."> tags pointing to the others. Google uses these to serve the correct language in search results. Our checker lists every hreflang tag and flags common errors: missing return links, incorrect language codes, or hreflang pointing to a 404.
The canonical tag tells Google which URL is the original when duplicates exist. A metadata checker reports the canonical and whether it is self-referencing or points elsewhere. If you see a canonical pointing to a different domain or a 404, that is a red flag. Use our canonical checker for deeper canonical diagnostics.
The viewport meta tag-<meta name="viewport" content="width=device-width, initial-scale=1">-controls mobile rendering. If it is missing, mobile browsers render the page at desktop width and scale it down, making text tiny. Google penalizes pages without a viewport tag in mobile-first indexing. Our checker flags the absence or reports the content value if present.
Common mistakes
- Setting OG title different from the HTML title. If
<title>is 70 characters andog:titleis 40, your Google snippet and social-share card have different copy. This confuses users. Keep them aligned unless you have a strong reason to differ. - Using a square image for
og:image. Twitter and LinkedIn expect 1200x630 or a 1.91:1 ratio. A square image gets cropped or letterboxed. Use the same aspect ratio everywhere. - Forgetting
og:url. This tag tells platforms the canonical URL to associate with the share. Without it, URL parameters like?ref=twittermight become the shared URL, creating duplicate engagement across variants. - No alt text on the OG image. Platforms do not display alt text for OG images, but screen readers and accessibility tools rely on it. If you use an
imgtag in your markup for the same image, set alt text there. - Setting
twitter:cardtosummarywhen you want the large image. The default is a small square thumbnail. Change it tosummary_large_imageto get the hero layout. - Deploying with test metadata. "Test post title" or "Lorem ipsum" in production happens more often than you think. A quick check before publishing catches this.
Advanced tips
- Use the Compare with field to diff your metadata against a competitor's top-ranking page. If their title is shorter, their description more specific, and they have schema while you do not, you know what to fix.
- Test the same URL with Desktop Chrome and Googlebot as user-agents. If metadata differs, your page is cloaking or serving different content to bots, which violates Google's guidelines.
- Check one page per template: homepage, product, category, blog post, landing page. Metadata errors are usually template-level, not page-level, so fixing one fixes hundreds.
- Look at the schema section. If you have multiple JSON-LD blocks, make sure they are valid and do not conflict. Two conflicting
@typedeclarations can cause Google to ignore both. - Test hreflang on multi-language sites. A missing return link-where the Spanish page points to the English page but the English page does not point back-breaks hreflang entirely.
- Download the report as JSON and diff it against a previous check. Use it in CI to catch metadata regressions when deploying a new theme or page builder.
After checking metadata, if warnings mention missing canonicals or hreflang mismatches, run the canonical checker to bulk-test URL variants. If schema warnings appear, re-validate with Google's Rich Results Test. To see how Googlebot actually renders the page-JavaScript execution, blocked resources, visible text-the google crawler simulator shows the raw and JS-rendered HTML side by side. For a broader on-page SEO audit that includes metadata, title length, H1, and internal links, use the SEO checklist.