Twitter card validator

X retired the preview in its own validator. Enter a URL here to see the card X will build and which tags it will use.

We fetch that one page's HTML (no JavaScript, no crawling), follow up to 4 redirects and discard it after the check.

How X picks each part of the card

Card partX reads firstFalls back to
Layouttwitter:cardnone (required; summary or summary_large_image)
Titletwitter:titleog:title
Descriptiontwitter:descriptionog:description
Imagetwitter:imageog:image
Image alt texttwitter:image:alt(up to 420 characters)
Attributiontwitter:site, twitter:creatoroptional @usernames

On the timeline, X currently shows the large-image card as the picture with the domain overlaid and the title hidden, so the image has to carry the message on its own. Keep text in the image large and centred.

Generate a matching set with the Twitter card generator.

Questions

What happened to the official Twitter Card Validator?

X removed the preview function from its Card Validator in 2022; the page now only points you to compose a post to see the card. This tool fills the gap: it fetches your page, applies X's documented tag rules and fallbacks, and draws the card.

Which tags does X need for a large image card?

twitter:card set to summary_large_image, plus a title and an image. X uses twitter:title and twitter:image if present and otherwise falls back to og:title and og:image. twitter:description (or og:description) is optional.

What image does X accept?

X's documentation lists JPG, PNG, WEBP and GIF (only the first frame of an animated GIF is used) under 5 MB. SVG is not supported. For summary_large_image, X specifies a 2:1 aspect ratio with a minimum of 300 × 157 pixels; for summary, a 1:1 image of at least 144 × 144 pixels.

Why does my card not show when I post the link?

Check that twitter:card is present and valid, that the image URL is absolute and publicly reachable, and that robots.txt does not block Twitterbot. X caches cards for a while, so changes may take time to appear on links that were already shared.

Sources