Which tags control a link preview
Chat apps and social networks fetch your page when someone pastes the link, read a few tags from the <head>, and build a card. Get them right and your link looks like a finished product; leave them out and it shows a bare URL or random text from the page.
| Tag | Used by | Best length |
|---|---|---|
<title> | Browser tab, Google, fallback for everything | Under 60 characters |
meta description | Google snippet, fallback text | Under 155 characters |
og:title, og:description | WhatsApp, Facebook, LinkedIn, Slack, iMessage, Discord | Same as above |
og:image | The big picture on the card | 1200×630 px, under 5 MB, absolute https URL |
twitter:card | X (Twitter) layout | summary_large_image when you have an image |
Previews on an HTMLtoLink page
Published pages are served with a noindex header, so they will not appear in Google — but link previews still work, because chat apps do not care about search indexing. Put these tags in your HTML before publishing, and every person you send the link to sees a proper card. The og:image must be an absolute URL: if your image is part of a ZIP upload, use https://your-name.htmltolink.dev/cover.png.
Why the preview did not update
Platforms cache previews, sometimes for days. Facebook's Sharing Debugger and LinkedIn's Post Inspector can force a refresh; for WhatsApp and Slack, adding a harmless query string such as ?v=2 makes the link look new.