OGImgA Pre-Launch Checklist for Testing Link Previews
Before you announce a page, check its preview in each platform's debugger, confirm the image URL returns a real PNG, and verify the tags on the live HTML rather than your local dev server.
A page is ready to share when the preview looks right on the platforms your readers use, not when it renders in your browser. Most preview bugs are invisible locally, because the crawler cannot reach localhost, sees the production HTML rather than your dev server's, and caches whatever it fetched the first time. This checklist catches them before the announcement goes out.
Check the live HTML
- Fetch the production URL with curl, not the browser, and confirm the og: and twitter: tags are in the raw response.
- Confirm og:url, the canonical link and the sitemap entry all name the same address.
- Confirm og:image is an absolute https URL and returns 200 with an image content type.
- Confirm there is exactly one og:image and one twitter:image on the page.
Check the platforms
Run the URL through the debugger for the platforms your audience uses. Facebook's Sharing Debugger, LinkedIn's Post Inspector and the X card validator are the usual three. Each shows the card as that platform reads it, including any warnings about the image size or a missing tag.
If a debugger shows an old card, scrape again or change the image URL as described in the stale-cache post. Do not assume the debugger is wrong.
Check the page itself
- Open the page on a phone-sized screen. Previews are the first impression, but the landing page is the second, and it should match the promise.
- Confirm the title in the browser tab is what you expect and is not the default framework title.
- Check that the page returns 200 and not a redirect to login, which would show a login screen as the preview.
Share it once, privately
Paste the final URL into a chat with yourself or a colleague and look at the preview as a reader would. This is the only check that catches a preview which is technically correct but looks wrong in context, such as a title that reads awkwardly under the image.
When all of this passes, you have done what the platforms can see. The rest is writing a good post for the people who click through.