Your link previews are broken and you've never looked

Every time someone pastes your link into Slack, LinkedIn, iMessage or a group chat, a bot fetches your page and builds a preview from a handful of tags. Most site owners have never looked at what it builds.

The tags that matter

• og:title and og:description: the headline and summary on the card.
• og:image: the picture. 1200 by 630 pixels is the common safe size.
• og:url: the canonical address of the page.
• twitter:card: set it to summary_large_image if you want the big image on X.

The tags come from the Open Graph protocol, and most platforms read them, not just Facebook.

What goes wrong

• No image, or the same image everywhere. Every page shares the logo, so every share looks the same and none of them stand out.
• Relative image URLs. og:image needs a full URL starting with https. /images/card.jpg often produces no image at all.
• Tags added by JavaScript. Preview bots generally read the raw HTML and don't run scripts. If a plugin or tag manager adds your Open Graph tags in the browser, the bot never sees them. It's the same problem as SEO pixels.
• Old previews that won't update. Platforms cache previews. After you fix the tags, use the platform's own tool, such as Facebook's Sharing Debugger or LinkedIn's Post Inspector, to fetch the page again.

The fix

Put the tags in the HTML your server sends, with a page-specific title, description and image, and an absolute image URL. Then look at the result before you share.

The free Meta & Social Preview (my own product) shows your Google snippet and your share card from the page's raw HTML, and lists the tags that are missing.