Slack link preview (unfurl) not showing? How to fix it
Slack calls link previews "unfurls" and builds them from your Open Graph tags: favicon, site name, title, description, image. Slack\u2019s cache is short compared to other platforms — so when an unfurl is broken, the problem is usually your tags or your bot protection, not the cache.
The free checker shows your previews for nine platforms — from X and WhatsApp to iMessage, Discord and Bluesky.
Set the tags Slack renders
og:title, og:description, og:image and og:site_name cover the unfurl. Slack also shows your favicon, so make sure that resolves too. Verify the whole set with the MetaPeek checker.
Let the scraper in
If your page requires a login or your WAF blocks non-browser requests, Slack shows just the bare URL. Make the page (or at least its <head>) reachable for bots — or test pre-deploy with the paste-HTML mode.
Choose image layout
A large 1200×630 og:image renders as a big card under the text; small images become the compact right-hand thumbnail. Pick the size accordingly.
Retest the right way
Slack caches unfurls briefly (think hours, not weeks). After a fix, post the link again in a fresh message — or use a ?v=2 variant if the old unfurl lingers.
Code example
<meta property="og:site_name" content="Your site name" />
<meta property="og:title" content="Your page title" />
<meta property="og:description" content="One or two short sentences." />
<meta property="og:image" content="https://yoursite.com/og-image.jpg" />Common mistakes
- Blaming the cacheSlack re-scrapes far more often than Facebook or X. A broken unfurl after a fix usually means the fix is not live yet, or the scraper is blocked.
- Internal or staging linksSlack cannot reach localhost, VPN-only staging or login-walled pages — no unfurl, by design. Test those with pasted HTML instead.
- Every message unfurling twiceIf both the link AND an og:video or rich media unfurl appear, Slack may stack them. Keep the tags simple: one title, one description, one image.
Frequently asked questions
Why does Slack show only the bare URL?
Slack could not scrape the page (blocked, login required, timeout) or found no usable tags. Users may also have previews disabled — check a different workspace before debugging your site.
How long does Slack cache an unfurl?
Short — typically hours. That makes Slack the platform where tag fixes show up fastest.
Can I remove a preview after posting?
Yes, click the ✕ on the unfurl in your own message. That only affects that message, not the cache.
Paste your URL and see within two seconds whether everything is right — on every platform.