How WhatsApp makes a preview
When someone types or pastes a link into a chat, WhatsApp fetches the page on behalf of the sender, before the message is sent, and builds the card from its Open Graph tags. The person receiving the message gets the preview the sender’s app made. That’s why fixing a page doesn’t change previews already sent, and why a page that blocks unknown bots can end up with no preview at all.
Checking your link
Give the checker your link in the Page URL tab. It is requested the way WhatsApp’s app requests it, with WhatsApp’s user agent, and the preview list and the live preview start with the WhatsApp chat bubble built from that response. The WhatsApp’s link preview rules panel then checks, one by one, what WhatsApp’s link preview documentation for developers asks for:
- og:title, og:description and og:url are present and not empty;
- the image is 300 pixels or wider, no wider than 4:1, and under 600 KB;
- the share tags end within the first 300 KB of the HTML.
Large preview or small thumbnail
The chat bubble shows the image large across the top when it meets the size rules, and as a small square beside the text when it doesn’t, for example a 250-pixel logo. A square or 1.91:1 image both work; keep text and faces in the middle, since the thumbnail crops to a square.
If the page passes here but WhatsApp still shows a bare link, open the Crawlers panel. A 403 or a bot challenge for WhatsApp’s crawler, while a browser gets the page, points to a firewall or CDN setting that needs an exception.
WhatsApp's published rules, as checked above
From Meta for Developers: WhatsApp Business Platform, "Link Previews", read on October 26, 2026. Once you check a page, the rules panel above tests it against every row a page's tags can break.
| What | WhatsApp's rule |
|---|---|
| Required tags | og:title, og:description and og:url inside <head>, none of them empty |
| Image (og:image) | an absolute URL, under 600 KB, 300 pixels or wider, no wider than 4:1 |
| Where the tags sit | the <head> must appear within the first 300 KB of the HTML |
| Who fetches it | WhatsApp crawls the link on behalf of the sender, while the message is being written |
| Guarantee | best effort: WhatsApp says previews should not be relied on |