Free tool
Link preview checker
See how a URL will look when it's shared on X, LinkedIn, Slack, Discord and iMessage, and which tags are missing or wrong. Nothing is stored.
No signup. Reads one public page, shows what it looks like today next to what it could.
What the score means
The checker reads the <head> of the page and looks for the tags platforms actually use to build a preview: og:title, og:description, og:image, twitter:card and a canonical URL. A missing image costs the most, because a link without an image gets a fraction of the space and attention of one with a large card.
The sizes that matter
| Platform | Large card |
|---|---|
| Open Graph / Facebook / LinkedIn / Slack | 1200×630 (1.91:1) |
| X (summary_large_image) | 1200×600 (2:1) |
| Instagram story | 1080×1920 (9:16) |
Keep text away from the outer 10% of the image, some apps crop. Keep the title under about 60 characters.