X / Twitter card preview
Rendered in your browser · nothing is uploaded
Renders the summary_large_image card X builds from your twitter: or Open Graph tags. Titles are cut around 70 characters and the description often disappears entirely on mobile.
How to use the x / twitter card preview
X changed this more than once and the current behaviour surprises people: on many surfaces it shows the image and the domain with the title overlaid, and drops the description altogether. That makes the image do almost all the work, and it makes a card with no image very weak. It collapses to a bare link. If you set nothing X-specific, X falls back to your Open Graph tags, which is usually fine and one less thing to maintain. Set twitter:card to summary_large_image explicitly, since the default small card is considerably less prominent in the timeline.
Questions
Not usually. X falls back to Open Graph tags, though setting twitter:card to summary_large_image is worth doing explicitly.
X drops it on several surfaces and shows the image with the title over it. The image carries the card.
1200 × 628 or thereabouts. The same 1200 × 630 Open Graph image works.
No, and it cannot be. Platforms cut by rendered pixel width, so a title in capitals or wide letters cuts earlier than a character count suggests. Treat the limit as a guide and leave a few characters of margin.
The small card shows a thumbnail beside the text; the large one shows a full-width image and is far more prominent.