Mastodon Open Graph
Test and debug your Open Graph tags for Mastodon
Mastodon Specs
| Image size | 1200x675px |
| Aspect ratio | 1.78:1 |
| Max file size | 5 MB |
| Formats | image/jpeg, image/png, image/webp, image/gif |
| User-Agent | Mastodon/4.3.0 (http.rb/5.2.0; +https://mastodon.social/) |
Mastodon generates preview cards when a URL is shared in a status, pulling data from Open Graph meta tags and oEmbed endpoints. Unlike centralized platforms, every Mastodon instance fetches and caches preview data independently, so your link can look different across the fediverse.
This guide covers how Mastodon’s per-instance crawling works, which tags it reads, image sizing rules, cache behavior, and the most common issues that prevent preview cards from appearing.
What links look like on Mastodon
The difference Open Graph tags make when sharing a link.
Without Open Graph
This site doesn't have Open Graph
opengraphplus.com
Mastodon Open Graph
Oh
With Open Graph
Sites with Open Graph look like this
opengraphplus.com
Mastodon Open Graph
Nice!
Debug Mastodon Open Graph tags
Enter your site's URL to see how it looks on Mastodon.