Slack Open Graph Preview Tool
Preview how your links appear on Slack. Test your Open Graph meta tags and optimize your Slack link previews for maximum engagement.
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Slack Open Graph Guide
How Slack Uses Open Graph Tags
Slack is a workplace communication platform that uses Open Graph tags to create rich link previews (unfurling) when users share URLs in channels, direct messages, and threads. Slack's implementation follows the standard Open Graph protocol.
Where Slack Shows Open Graph Previews
- Channels - Link previews in public and private channels
- Direct Messages - Rich embeds in 1-on-1 conversations
- Group DMs - Preview cards in group conversations
- Threads - Link previews in message threads
- Shared Channels - Embeds in shared channels between workspaces
Slack Image Dimensions & Requirements
- Optimal size: 1200×630px (1.91:1 aspect ratio)
- Minimum size: 200×200px
- Maximum file size: 5MB (aim for under 1MB)
- Supported formats: JPG, PNG, GIF, WebP
Required Slack Open Graph Tags
<!-- Essential Open Graph Tags for Slack -->
<meta property="og:title" content="Your Page Title" />
<meta property="og:description" content="Your page description" />
<meta property="og:image" content="https://example.com/image.jpg" />
<meta property="og:url" content="https://example.com/page" />
<meta property="og:type" content="website" />Recommended Additional Tags
og:site_name- Your site or company nameog:image:widthandog:image:height- Image dimensionsog:image:alt- Alt text for accessibility
Slack Link Unfurling Process
- User shares a URL in Slack
- Slack's servers fetch the URL
- Slack parses Open Graph tags from the HTML
- Slack displays a rich preview card
- Preview is cached for future shares
Slack Caching Behavior
- Slack typically caches for 24-48 hours
- No official Slack cache-clearing tool
- Use query parameters to create a "new" URL
- Ensure server responds within 3-5 seconds (Slack has timeout limits)
Workplace Optimization Tips
- Use professional, workplace-appropriate images
- Keep descriptions under 200 characters
- Focus on business value and outcomes
- Test on both light and dark Slack themes
Slack Open Graph FAQ
What image size should I use for Slack link previews?
Slack recommends 1200×630px (1.91:1 aspect ratio) for optimal display. Minimum size is 200×200px, but larger images provide better quality. Maximum file size is 5MB, aim for under 1MB for faster unfurling.
How long does Slack cache Open Graph data?
Slack typically caches Open Graph data for 24-48 hours. There's no official cache-clearing tool, so you may need to wait or use query parameters (e.g., ?v=2) to create a "new" URL that bypasses cache.
What is Slack link unfurling?
Slack link unfurling is the automatic process where Slack expands shared URLs into rich preview cards using Open Graph tags. Slack fetches the URL, parses OG tags from the HTML, displays a preview card, and caches for future shares.
What are the required Open Graph tags for Slack?
Slack requires standard OG tags: og:title, og:description, og:image, og:url, and og:type. Also include og:site_name for better branding in Slack previews.
Why is my Slack link preview not showing?
Common issues: 1) Server response is too slow (Slack has timeout limits), 2) Meta tags are rendered client-side only, 3) Image URLs are relative, 4) Cache issues. Ensure your server responds within 3-5 seconds.
How do I optimize link previews for workplace use?
Use professional language and imagery, emphasize business value and outcomes, keep descriptions under 200 characters (Slack truncates long text), and ensure your previews match the professional tone of workplace communication.
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