PreviewChecks

Find why link previews fail

Debug social cards before links are shared.

OGXFacebookLinkedInPinterestSlack/Telegram/Discord
Preview image appears here after a check.

example.com

Your social preview title

The description will show how your link may appear before people click it.

First useful check

Get a clear answer in minutes

The first report should tell you whether a social crawler can reach the page, which preview image will be chosen and what to fix before launch.

Paste a public URL

Start with the page you plan to share, not a staging URL behind auth.

Read the summary first

Fix blocking crawler, image or metadata issues before smaller warnings.

Use the API for repeats

Move stable checks into release scripts once the web report looks right.

Why it matters

A broken preview costs clicks before the page loads

Social apps cache link cards fast. If the title is cropped, the image is missing or a crawler hits a challenge page, the shared link looks unfinished until the cache is refreshed.

Preview images

Find broken URLs, redirects, wrong ratios, missing dimensions and files that are too large.

Crawler access

See when bot protection, challenges or server responses can block social preview crawlers.

Platform rules

Check Open Graph, X cards, chat unfurls and Pinterest requirements from one report.

Use cases

Use it before every public share

  • OKCheck a landing page before launch.
  • OKDebug a blog post that shares without an image.
  • OKVerify that WAF rules do not block preview crawlers.
  • OKCompare X, Facebook, LinkedIn, Slack, Telegram and Pinterest output.

Guides

Fix the usual preview failures

Open Graph image order

Why the first wide image should be the safest default for most previews.

Crawler access

How to allow real social crawlers without trusting user-agent strings.

Pinterest images

When a portrait image belongs in structured data instead of replacing your main OG image.

API

Validate previews from your own tools

The public API returns the same backend report used by this page: crawler access, platform checks, image candidates, metadata and fixes.

Current fair-use limit: about 20 checks per minute for the same IP and target host, with a higher per-IP ceiling across all hosts.

Request

Pass a page URL. Bare domains are normalized to HTTPS.

Response shape

The API returns one JSON object with the normalized request URL, final URL, summary score, preview title, description, image, TLS 1.2 compatibility, platform checks, crawler results, detected metadata and ordered fixes.

FAQ

Questions people ask when previews fail

Why does a link preview need meta tags?
Social apps do not render your whole page like a browser. They read metadata, choose a title, description and image and cache the result.
Which image should be first?
Use a 1200x630 wide image first. It fits Open Graph, Facebook, LinkedIn and most chat previews. X large cards also work well with 1200x628 or a close 1.91:1 wide image.
What about Pinterest?
Pinterest can use a portrait image for Rich Pins. Keep the wide Open Graph image first for common previews and add a portrait image in structured data when Pinterest matters.
Do image redirects matter?
Yes. A direct image URL is safer. Redirects can fail under bot protection, cache rules or stricter fetchers.
Why does my preview still show the old image?
Social platforms cache previews and image proxies separately. First confirm your server and CDN serve the new HTML and image, then use the platform debugger when one exists. If the old image still appears, change the og:image URL with a versioned filename or query parameter that your CDN cache key respects.
Can WAF or bot protection block previews?
Yes. Real social crawlers should be allowed by verified crawler rules, not by user-agent alone. User-agent allowlists are easy to spoof.
Why do you simulate crawlers?
The checker compares a normal fetch with crawler-like fetches. This helps spot WAF risk, but it is not the same as a verified request from a social platform IP range.
Is PreviewChecks free?
Yes, for now. It is a public tool with fair-use limits so the service stays available for everyone.
What is the API rate limit?
The public API currently allows about 20 checks per minute for the same IP and target host, with a higher per-IP ceiling across all hosts. We may lower or block abusive traffic.
Do you store checked URLs?
No account and no check history are stored by PreviewChecks. Cloudflare may process standard request, security and performance data for delivery and abuse protection.
Does this replace official debuggers?
No. It gives one clear report before you use official tools. Some platforms do not provide a debugger anymore and only publish guides or recommendations.