Link preview checker / Slack unfurl preview
Slack link preview checker
Paste a URL to see how Slack unfurls it: the site name, title, description and image it takes from your page's tags.
You don't need an account. Paste any public page and see what X, LinkedIn, Slack, Discord, WhatsApp, Facebook and iMessage will show.
What Slack needs from your page
- Tags it reads
- Open Graph and Twitter tags (og:title, og:description, og:image, og:site_name), plus oEmbed where a site offers it.
- Image
- A wide image shown below the text; 1200×630 works well.
- Who fetches it
- Slack's own crawler (Slackbot-LinkExpanding). Pages behind a login or blocked to bots won't unfurl.
- Refreshing an unfurl
- There is no way to flush the cache; unfurls expire on their own. A changed URL (?v=2) unfurls fresh straight away.
Questions
Why isn't my link unfurling in Slack?
Slack's crawler may be blocked by a firewall or robots rule, the page may need a login, or it has no Open Graph tags. Check the link here to see what a crawler can read.
How do I refresh a Slack unfurl?
Slack doesn't offer a way to clear its cache. Share the URL with a small change, such as ?v=2, and Slack reads it as a new link.
Can I stop Slack from unfurling a link?
Whoever shares it can remove the preview from their message. Site-wide, Slack follows robots rules for its crawler.
Fix it once, for every page
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