Every time someone shares your page on LinkedIn, Facebook, X, Slack or Teams, the platform builds a card from your Open Graph tags — silently. Check what it sees before you hit publish.
Updated August 2026 · 5 minute read
When a URL is pasted into a social network or chat app, that platform's crawler fetches your page and reads four meta tags from the og: namespace: og:title, og:description, og:image and og:url. X (Twitter) uses its parallel twitter:card tags, falling back to Open Graph when they are missing.
If the tags are absent, the platform guesses — usually badly: no image, a truncated title, or a description scraped from random page text. If the tags are wrong, the wrong card shows, and the platforms cache aggressively: fixing the tags today does not fix cards already cached.
The single most common failure: og:image missing, relative instead of absolute, smaller than 200×200 px, or pointing at a URL behind auth. Any of these renders no image at all.
Facebook and LinkedIn cache share data for days. Fix tags first, then use each platform's debugger to force a re-scrape — otherwise you're testing stale data.
A good checker validates every tag at once: presence, sizes, absolute URLs, image dimensions and twitter:card fallbacks.
Option A — automated (recommended). Paste your URL into the free page profiler. Alongside the full technical SEO report you get the complete Open Graph and Twitter Card picture: which tags exist, whether og:image resolves and meets size minimums, and whether twitter:card has sane fallbacks.
Option B — view-source. Open your page, view source, and search for og:. You should find at least title, description, image and url inside the <head>. Remember: tags rendered client-side by JavaScript are invisible to most platform crawlers — they must be in the raw HTML response.
Option C — platform debuggers. After fixing, run Facebook's Sharing Debugger and LinkedIn's Post Inspector to refresh their caches and confirm the new card. Each platform caches independently; clearing one does not clear the others.
1200×630 px, absolute URL, under ~8 MB, publicly reachable, PNG or JPEG. That passes every major platform's requirements with margin.
Cards truncate around 55–65 characters of title and ~110–160 of description depending on platform. Put the important words first.
One shared set of OG tags across a whole site means every shared article shows the homepage card. Generate them per template — most CMSs do this with one plugin or one meta partial.
1. Missing og:image entirely. Posts without images get dramatically less engagement on every platform. This is the highest-value fix on this list.
2. Relative image URLs. <meta property="og:image" content="/img/cover.jpg"> works in a browser but renders nothing in a share preview. Always absolute.
3. JavaScript-injected tags. Platform crawlers mostly do not execute JS. If your SPA sets OG tags at runtime, shares show nothing. Render tags server-side.
4. Identical tags everywhere. Template-level defaults leaking onto articles make every share look identical — and users stop clicking.
5. Forgetting twitter:card. Without twitter:card (usually summary_large_image), X falls back to a small plain summary. One line fixes it.
Yes. The page profiler runs in your browser, needs no account, and covers Open Graph, Twitter Cards plus the rest of your page's technical health in the same report.
Platform caches. Use Facebook's Sharing Debugger and LinkedIn's Post Inspector to force a re-scrape after deploying changes. Until then you are looking at old cached data.
Not directly — Google reads title/meta description, not og: tags, for ranking. But share previews drive clicks and traffic, and a broken preview quietly kills that channel.
All read Open Graph tags. The same rules apply: absolute image URLs, server-rendered tags, sensible dimensions.
There is a Danish technical SEO guide and a fully Danish profiler at /da/page-profile.
Yes — the companion Python CLI outputs JSON for any URL, so a pipeline can fail a build when og:image goes missing. See the technical SEO check guide.