# Slack unfurl preview checker

> Slackbot unfurls links using the favicon, og:site_name, title, description and image.

Check a URL: https://sharelint.pages.dev/?url=<your-url>, or as Markdown: https://sharelint.pages.dev/api/preview?format=md&url=<your-url>

## Tags Slack reads (fallback order)

- Site: `og:site_name` -> `favicon`
- Title: `og:title` -> `twitter:title`
- Description: `og:description` -> `twitter:description`
- Image: `og:image` -> `twitter:image`

## Image requirements

- Recommended: 1200×630
- Minimum: none documented
- Maximum weight: none documented
- Formats: JPEG, PNG, GIF

## Card layout

A thumbnail on the right by default. summary_large_image shows a larger image below.

## Refreshing the cache

Slack caches unfurls for about 30 minutes. Add a query string to force a new fetch.

## Common problems

- No unfurl: the page blocks Slackbot in robots.txt, or responds too slowly.

Rule confidence: documented.