Facebook requires these OG tags for a proper link preview:

Without og:image, Facebook may pull a random image from your page or show no image at all. Without og:url, Facebook cannot consolidate share counts.

fb:app_id — The Facebook Sharing Debugger shows a warning if fb:app_id is missing. This tag is effectively deprecated for most use cases. It was originally required to access Facebook Insights for shared links, but that feature has been discontinued.

The warning does not affect how your link preview renders. You do not need to create a Facebook App just to suppress it.

fb:admins — A legacy tag that granted specific Facebook users admin access to insights for a domain. No longer necessary.

Facebook is strict about image specifications. The recommended size is 1200 x 630 pixels with a 1.91:1 aspect ratio. The minimum size is 200 x 200 pixels, and the maximum file size is 8 MB. Supported formats include JPEG, PNG, GIF, and WebP. Image URLs must be absolute (HTTPS preferred).

Images below 600 x 315 pixels will render as a small square thumbnail instead of a large preview card. Always aim for at least 1200 x 630 to get the large card format.

Specifying og:image:width and og:image:height lets Facebook render the card layout before downloading the image, preventing layout shifts.

Facebook's crawler identifies itself as facebookexternalhit/1.1. Key behaviors:

No JavaScript execution. The crawler reads raw HTML only. If your OG tags are injected client-side via JavaScript, Facebook will not see them.

5-second timeout. If your server takes longer than 5 seconds to respond, the crawl fails.

Follows redirects. Up to 5 redirects, then gives up.

Respects robots.txt for the facebookexternalhit user agent. Blocking this agent means no link previews.

IP ranges. Facebook crawls from multiple IP ranges. Do not whitelist by IP; use the user agent string instead.

Facebook caches scraped OG data aggressively:

Cache duration: approximately 30 days from the last scrape.

HTTP vs HTTPS: Cached separately. http://example.com/page and https://example.com/page have independent caches.

First share triggers a scrape. The first person to share your URL triggers the initial crawl. Subsequent shares within the cache window use the cached data.

To force a cache refresh, use the Sharing Debugger or the Graph API (see below).

The Facebook Sharing Debugger is at developers.facebook.com/tools/debug/. You must be logged into a Facebook account to use it.

Step-by-step: Go to the Sharing Debugger. Enter your URL in the input field. Click Debug. Review the parsed OG tags, warnings, and the preview card. If you have updated your tags and the preview is stale, click Scrape Again. Click Scrape Again a second time if the first scrape still shows old data — Facebook sometimes needs two attempts.

The debugger shows all OG tags it found on your page, warnings for missing or invalid tags, a preview of how the link will appear in the feed, and the time of the last scrape.

Use the Facebook Graph API to clear the cache programmatically. This is useful after deploying content changes or in CI/CD pipelines.

The access token can be an App Token (no user login required): APP_ID|APP_SECRET. You can generate this from your Facebook App dashboard.

For batch cache clearing across multiple URLs:

Rate limit: approximately 50 scrape requests per minute per app.

Missing Required Property: og:image — No og:image tag found. Fix: add an og:image meta tag with an absolute URL.

og:image could not be downloaded — Image URL returns 404, times out, or is blocked. Fix: verify the image URL loads in a browser; check server response time.

og:image is too small — Image dimensions below 200x200. Fix: use at least 1200x630 pixels.

Share rate limit reached — Too many scrape requests. Fix: wait and try again in a few minutes.

Inferred Property — Facebook guessed a value instead of reading it from a tag. Fix: add the explicit OG tag to stop Facebook from guessing.

Object Missing a Required Value — og:title, og:type, or og:url is missing. Fix: add the missing required tag.

fb:app_id hasn't been included — No fb:app_id on the page. Safe to ignore; does not affect preview rendering.

Could not parse og:image — Image format is unsupported or corrupt. Fix: re-export the image as JPEG or PNG; verify the file is not corrupt.

Redirect Path Too Long — More than 5 redirects before reaching the final URL. Fix: reduce your redirect chain.

For blog posts, news articles, and editorial content, set og:type to article and add these properties:

article:author should be a URL to the author's profile page (or their Facebook profile URL). article:published_time and article:modified_time use ISO 8601 format. You can include multiple article:tag entries.

Facebook uses article:published_time to display the publication date in the link preview, which helps establish content freshness.

Here is a complete, minimal example with all required OG tags and article properties:

og:title — Required. Max ~88 characters displayed.

og:description — Recommended. Max ~300 characters displayed.

og:image — Required. 1200x630 recommended, min 200x200.

og:image:width — Recommended. Prevents layout shift.

og:image:height — Recommended. Prevents layout shift.

og:image:alt — Recommended. Accessibility.

og:url — Required. Canonical URL.

og:type — Required. website, article, profile, etc.

og:site_name — Optional. Site-level name.

og:locale — Optional. Defaults to en_US.

fb:app_id — Not required. Warning is safe to ignore.

article:published_time — Optional. ISO 8601 datetime.

article:modified_time — Optional. ISO 8601 datetime.

article:author — Optional. URL to author profile.

article:section — Optional. Content category.

article:tag — Optional. Multiple allowed.