Why does my link preview not show an image?

The usual cause is a relative og:image URL. Crawlers require an absolute one, so /card.png silently produces a text-only card. The second most common cause is serving the image over plain http, which several platforms refuse.

I fixed my tags but the old preview still shows. Why?

Every platform caches unfurled links aggressively, often for days, keyed on the URL. Ask the platform to re-scrape it — Facebook's Sharing Debugger or LinkedIn's Post Inspector — or add a query parameter to get a fresh URL. This tool shows what a crawler will fetch next time, not what the platform currently holds.

Do I need twitter: tags if I already have Open Graph?

Usually not. X falls back to og: tags for anything missing, so a complete Open Graph set plus twitter:card is enough. Add the twitter: variants only when you want X to show something different from everywhere else.

OG Inspectorserver-backed

Read a page's title, description and social tags, and see the card people will share.

Enter a URL to read its metadata.

R3X reads the HTML the server sends. Tags added later by JavaScript will not appear here — and crawlers will not see them either.

Runs on R3X infrastructure. The page is fetched by an R3X server so its markup can be read. The URL is not stored, and the page is discarded once its tags have been extracted.

Reference

It reads the served HTML, not the rendered page

R3X fetches the document your server sends and parses that. It does not run JavaScript — and neither do most crawlers. If your tags are injected client-side, they are invisible here and invisible to Slack, Discord, iMessage and every social platform's unfurler, which is exactly the bug this tool exists to make obvious.

Which tag wins

Platform	Order it reads
Facebook, LinkedIn	og:* only. No fallback to twitter:* tags.
X	twitter:* first, then og:* for anything missing.
Slack, Discord	og:* first, then oEmbed, then <title> and meta description.
Search engines	<title> and meta description. Open Graph tags are not used for the search snippet.

In practice a complete set of og: tags plus twitter:card covers everything. Duplicating every field into twitter: is only worth doing when you want X to show something different.

og:image

It must be an absolute URL — a relative path is the single most common reason a card renders as text. Serve it over https, keep it near 1200×630, and remember that most platforms will not follow a redirect to reach it.

The preview here loads the image only after you click, and it loads it directly from the target site with no-referrer. That is a deliberate choice: proxying it through R3X would make this page an open image relay, and loading it automatically would tell the target site your IP address every time you inspected a URL.

Why the card you see may not match a real share

Every platform caches aggressively — often for days, keyed on the URL. After fixing a tag you generally need to ask the platform to re-scrape it: Facebook's Sharing Debugger, LinkedIn's Post Inspector, or simply appending a query parameter to get a fresh URL. What you see here is what the platform will fetch next time, not what it currently holds.

Questions

Why does my link preview not show an image?: The usual cause is a relative og:image URL. Crawlers require an absolute one, so /card.png silently produces a text-only card. The second most common cause is serving the image over plain http, which several platforms refuse.
I fixed my tags but the old preview still shows. Why?: Every platform caches unfurled links aggressively, often for days, keyed on the URL. Ask the platform to re-scrape it — Facebook's Sharing Debugger or LinkedIn's Post Inspector — or add a query parameter to get a fresh URL. This tool shows what a crawler will fetch next time, not what the platform currently holds.
Do I need twitter: tags if I already have Open Graph?: Usually not. X falls back to og: tags for anything missing, so a complete Open Graph set plus twitter:card is enough. Add the twitter: variants only when you want X to show something different from everywhere else.