Slack Open Graph
Test and debug your Open Graph tags for Slack
Slack Specs
| Image size | 1200x630px |
| Aspect ratio | 1.9:1 |
| Max file size | 5 MB |
| Formats | image/jpeg, image/png, image/webp, image/gif |
| User-Agent | Slackbot-LinkExpanding 1.0 (+https://api.slack.com/robots) |
Slack generates “unfurl” previews when someone pastes a URL in a channel, reading Open Graph and Twitter Card meta tags to build an inline card with a title, description, and image. A key gotcha is that Slackbot only fetches the first 32KB of your page – so your meta tags need to appear early in the HTML.
This guide covers how Slackbot crawls pages, which tags it reads (including oEmbed and the bonus twitter:label/twitter:data fields), image sizing, the 30-minute global cache, and the most common issues that prevent unfurls from appearing.
What links look like on Slack
The difference Open Graph tags make when sharing a link.
Without Open Graph
This site doesn't have Open Graph
Slack Open Graph
Oh
With Open Graph
Sites with Open Graph look like this
opengraphplus.com
Slack Open Graph
Nice!
Debug Slack Open Graph tags
Enter your site's URL to see how it looks on Slack.