Exploration prototype · free · not for sale · runs in your browser; nothing is uploaded and no page or image is fetched
What will your link look like when someone shares it?
Paste the HTML of your page and see the title, description and image that LinkedIn, X, Facebook, Slack and WhatsApp would most likely show — and why a preview has the wrong title, no image or a cut text. Then copy corrected meta tags.
Check a pageWhat it does not check →
Rules follow the Open Graph protocol and the platforms' own documentation, checked on 2026-10-31. Every finding names its source.
problem
og:imagerelative URL /images/mugs-share.jpgwarning
og:image 800 × 800below LinkedIn's 1200 × 627 minimumwarning
og:urldiffers from the canonical linkCheck your page
Runs in your browser. Nothing is sent to us or to any site.
How it reads your page
- Reads the tags as text. Your HTML is scanned as a string, the way the HTML standard tokenizes it: comments, scripts and styles are skipped, attributes may come in any order and in any quotes, character references such as & are decoded. It is never run or shown as a page.
- First tag wins. If a tag appears twice, the first one counts — ogp.me: “The first tag (from top to bottom) is given preference during conflicts.” For twitter:* tags X documents nothing on duplicates; we assume the same and say so.
- Follows each platform's documented order. X falls back from each twitter:* tag to its Open Graph tag; Slack reads Open Graph and X Card tags; Facebook guesses with “internal heuristics” when Open Graph is missing. Where a step is not documented, the card says it is a guess.
- Compares with published figures. LinkedIn: image at least 1200 × 627 px, ratio 1.91:1. Facebook: 1080 px wide recommended (its 600 px figure is for image link ads, not ordinary previews). X: summary image at least 144 × 144, large image at least 300 × 157, title at most 70 and description at most 200 characters. No other platform publishes a length limit, so none is invented here.
Sources
Checked on 2026-10-31. WhatsApp publishes no documentation on link previews that we could find; its card uses the Open Graph values as an assumption.
| Source | Used for |
|---|---|
| The Open Graph protocol (ogp.me) | Required tags (og:title, og:type, og:image, og:url), first tag wins, og:image:* belongs to the og:image before it, og:image:alt, property= syntax, tags in <head>. |
| X Developer Platform: Cards markup tag reference checked on the Internet Archive copy of 2025; the live address now leads to the X developer home page | Fallback from twitter:* to Open Graph, card types, summary card without twitter:card, title 70 / description 200 / image alt 420 characters, no SVG. |
| X Developer Platform: Summary card Internet Archive copy of 2025 | Summary card image: 1:1, at least 144 × 144, at most 4096 × 4096, cropped to a square. |
| X Developer Platform: Summary card with large image Internet Archive copy of 2025 | Large image card: 2:1, at least 300 × 157, at most 4096 × 4096. |
| Meta for Developers: A guide to sharing for webmasters the page renders only with JavaScript; checked on the Internet Archive copy of 2025 | og:url as the canonical URL, internal heuristics without Open Graph, og:image:type values, secure_url, declaring image width and height. |
| Meta for Developers: Sharing best practices Internet Archive copy of 2025 | Image width: 1080 px recommended “for best display on high resolution devices” (the 600 px minimum it names is “to display image link ads”); width and height let the crawler render the image immediately. |
| LinkedIn Help: Make your website shareable on LinkedIn | og:title, og:image, og:description and og:url must exist; image at least 1200 × 627 px, ratio 1.91:1; its own example uses “//” URLs. |
| Slack developer docs: Unfurling links in messages (classic unfurling) | Classic unfurling reads Open Graph and X Card metadata. |
| HTML Living Standard: parsing | How the HTML is tokenized: comments, raw-text elements, attributes, character references, <title>. |
| RFC 6596: The Canonical Link Relation | A canonical link names the preferred URL of the page (checked for a non-http(s) value). |
Refresh the previews
Platforms cache a preview when a link is first shared. After you change your tags, ask them to read the page again:
- Facebook: Sharing Debugger — developers.facebook.com/tools/debug/
- LinkedIn: Post Inspector — www.linkedin.com/post-inspector/
- X, Slack and WhatsApp: the sources above name no public inspector. Their previews update when they read the page again; when that happens is not documented.
Limits of this prototype
- An approximation of documented behaviour. Platforms change their rules and layouts without notice and do not document everything; the cards are not screenshots.
- Cached previews. A platform may keep showing an old preview until it reads your page again (see above).
- The text you paste. It does not fetch the live page, so it cannot tell whether your server sends the same HTML to the platforms' crawlers, whether robots.txt, a firewall or a login blocks them, or whether tags are added later by JavaScript.
- Images are not loaded. Their real size, file size and format are not checked — only the URL and the size your page declares.
- Lengths. Only X documents maximum lengths. How much of a long title the others show depends on the layout and is not documented.
An exploration prototype built by the 28/28 AI venture builder to learn whether this is useful. It makes no claim of demand and sells nothing. Your HTML never leaves your browser; see the privacy policy for this website.