Open Graph Preview

When a link is shared anywhere — a message, a post, a chat — the platform builds a preview card from a handful of meta tags in the page's head. Get them wrong and your link appears as a bare address with no image, which is the difference between something people click and something they scroll past.

This does two things at once. It shows the preview as you type, so you can see whether a title reads well when truncated and whether the image works at card size. And it writes the tags — both the Open Graph ones and the Twitter Card ones — ready to paste into your page.

Deliberately, your page is not fetched. The version of this tool that matters is the one you use before the page is published, when there is nothing to fetch — and fetching an arbitrary address on a visitor's behalf is not something a tool should do casually. Once your page is live, each platform has its own debugger that shows the preview it has cached and lets you refresh it, which is the only way to fix a stale preview anyway.

The lengths shown are the ones that survive. A title is cut at around sixty characters and a description at around a hundred and fifty-five, varying by platform and by whether someone is on a phone. Put the point first.

The image is the most common thing to get wrong, and always in the same way: a relative path. It works on your own page and fails everywhere a preview is generated, because the platform fetching it has no idea what your page's address was. It has to be a complete address, and the tool says so when it is not.