Will your link look broken when shared?
Paste your page and we check whether it has the Open Graph title and image tags a link preview is built from - so you know whether it'll unfurl as a clean card or a bare, blank box. Free, no signup.
What we check
When someone drops your link into iMessage, Slack, X, LinkedIn, or a WhatsApp chat, the card that unfurls is built from Open Graph meta tags in your page's head. The two that decide whether you get a card at all are og:title and og:image. We read the page you submit and check whether those tags are present, so you know the link won't unfurl as a bare, blank rectangle.
This is a presence check on the page you give us: we confirm the title and image tags are declared in the markup. We don't fetch the image to confirm it loads, and we don't re-render the card for every platform, since each one (X, Slack, Facebook) caches and crops a little differently. A declared image that 404s is beyond what a tag check can see - this catches the far more common break, the tag that simply isn't there.
Why it matters
A missing preview image is the kind of thing nobody notices until the link is already out. You ship a launch post, paste your URL, and instead of a clean card with your product shot it unfurls as a gray box with a naked link. It still works - it just looks broken, and on a feed full of polished cards, broken-looking gets scrolled past.
The tags are easy to forget and easy to lose: a template that never set them, a migration that didn't carry them over, a CMS that strips the head on publish. You only find out when the post is live and the first reply is 'your link's broken.' Checking takes a few seconds, before you hit publish.
Questions
What tags do you check?
The two Open Graph tags a link preview can't render without: og:title and og:image. Those are what platforms read to turn your link into a card, and a missing one is what drops it to a blank box. We read them from the page you submit.
Do you render the actual preview card?
No. We confirm the title and image tags are present in the page you give us. Each platform crops, caches, and styles the card its own way, so the only honest check is whether the tags that build it are there - which is the part that's actually missing when a preview breaks.
Why does my image work on one platform but not another?
Usually caching or size rules on the platform's side. One may have cached an older version, or your image may be below its minimum dimensions. We check that the image tag is declared; clearing a platform's cache or running its own debugger handles the stale or mis-sized ones.
Is it really free?
Yes. Paste a URL and run it, no account needed. The same scan also runs all of CopyMosaic's other checks, and you can open the full report to see them.