Link Preview
A link preview is the card with an image, title, and description that appears when a URL is shared on social media or a messaging app. It gives people a snapshot of the destination before they click. Platforms build the preview from meta tags in the page’s HTML, so what shows up is controlled by the site, not the person sharing the link.
How Link Previews Work
When you paste a URL into a post or chat, the platform sends a bot to fetch the page and read its meta tags. It pulls three things: a title, a description, and an image. Then it renders those into a card below your text.
Most platforms read Open Graph tags for this data. Facebook, LinkedIn, Slack, WhatsApp, Discord, and iMessage all use the same Open Graph tags that Facebook introduced in 2010. X (Twitter) reads its own Twitter Card tags but falls back to Open Graph when those are missing.
The preview is cached. The first time a link is shared, the platform scrapes the page and stores the result. Later shares of the same URL reuse that stored card, even if the page changed. This is why a fix to an image or title often does not show up until you force a re-scrape.
What a Link Preview Contains
A standard link card has four parts:
- Image: the visual thumbnail, pulled from the
og:imagetag. The most eye-catching element. - Title: the headline, from
og:title. Usually shown in bold. - Description: the summary line below the title, from
og:description. - Domain: the source website, shown in small text so people know where the link leads.
When these tags are missing, the platform guesses. It might grab the first image on the page, a stray line of body text, or nothing at all. The result is a bare or broken card that gets scrolled past.
Link Preview Image Sizes
Use 1200 x 630 pixels for the preview image. That is a 1.91:1 aspect ratio, and it fills the card on Facebook, LinkedIn, Slack, and WhatsApp without cropping.
Keep these rules in mind:
- Format: JPG for photos, PNG for logos and sharp text.
- File size: under 1MB loads fast and avoids caps.
- Absolute URL: the image path must be a full URL, not a relative one.
- Safe zone: keep text and faces near the center so mobile crops do not cut them off.
X supports two card styles: a small summary card with a square thumbnail, and a summary_large_image card. For the large X card, 1200 x 675 (16:9) works well.
How to Check a Link Preview
Test the card before you share the link publicly. Each major platform has a free debugger: Facebook’s Sharing Debugger, LinkedIn’s Post Inspector, and X’s Card Validator. These tools show the rendered preview and let you force a re-scrape after you update tags.
If you shorten links for campaigns, confirm the short URL passes the preview through correctly. A link preview tool shows exactly how a shared link renders across platforms, so you can catch a missing image or wrong title before it goes live.
Common Link Preview Problems
The most frequent issue is stale caching. Platforms store the first card they scrape, so an updated image will not appear until you re-scrape through the debugger. A relative og:image path is the next most common error, since platforms require an absolute URL. Missing tags entirely leave the card blank. Short links can also strip previews if the redirect does not carry the destination’s meta tags through.
Frequently Asked Questions
What is a link preview?
A link preview is the card, made up of an image, title, and description, that appears when you share a URL on social media or a messaging app. It gives a snapshot of the page before anyone clicks. Platforms build it from meta tags in the page’s HTML.
How do I change a link preview?
Edit the page’s Open Graph tags: og:title, og:description, and og:image. Then run the URL through the platform’s debugger to force a re-scrape. Because previews are cached, changes will not appear until the platform fetches the page again.
Why is my link preview not showing an image?
Usually the og:image tag is missing, uses a relative path instead of a full URL, or the image is too large. A cached preview from before the image was added can also be the cause. Force a re-scrape in the platform debugger to refresh it.
Do link previews affect SEO?
Not directly. Link previews do not change Google rankings. They raise click-through rates from social media, which drives traffic and can create indirect SEO value through engagement and shares.
To see how your shared links render before you post them, check the link preview feature at linkutm.