What X shows when someone shares your link
When a link is posted, X reads a few tags from the page’s HTML and builds a card from them: an image, a title and your domain. The twitter:card tag picks the layout. summary_large_image shows your image across the whole card, summary shows a small square next to the title.
For the title, description and image, X looks for its own twitter: tags first and uses your Open Graph tags (og:title, og:description, og:image) when they’re missing, as X’s card guide explains. So if your Open Graph tags are right, you often only need to add twitter:card.
Why the card doesn’t show
- There are no card or Open Graph tags at all, which is common in apps that build every page in the browser.
- The image address isn’t a full
https://address on your own domain. - The image doesn’t load, is blocked, or is still the default picture from your builder.
- The tags are added by JavaScript after the page loads. X reads the HTML your server sends, not the page after it runs.
An image of 1200 × 630 pixels works well on X and on every other site that shows link previews.
How to see X’s own preview
Paste the link into a draft post on X. The card appears before you publish. If you just fixed your tags and still see the old card, give it time, because X keeps a copy of each card for a while.