# 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) |

[Official docs](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.