| Image size | 1200x630px |
| Aspect ratio | 1.9:1 |
| Max file size | 5 MB |
| Formats | image/jpeg, image/png, image/webp, image/gif |
| User-Agent | facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php) |
Facebook invented the Open Graph protocol, so its crawler is the reference implementation for OG tags. When a URL is shared on Facebook, Messenger, or Instagram, the facebookexternalhit crawler fetches the page and builds a link preview from your meta tags.
This guide covers how Facebook’s crawler works, which tags you need, image sizing, cache behavior, and the most common issues that prevent previews from displaying correctly.
Understanding facebookexternalhit and how it fetches your link previews
Which meta tags Facebook uses and the four required properties
Image sizes, aspect ratios, and format requirements for Facebook link previews
How Facebook caches link previews and how to force a refresh
Troubleshooting the most frequent Facebook link preview problems
Enter your site's URL to see how it looks on Facebook.