Why this tool asks for tags instead of a URL
A browser cannot fetch another site's HTML — the same-origin policy blocks it, which is the security rule that stops any page you visit from reading your webmail. Tools that accept a URL do the fetching on their own server. This one runs entirely in your browser, so you paste the tags instead. Open the page you want to test, press Ctrl+U to view source, and copy the <head> block.
What each platform reads
Facebook, LinkedIn, WhatsApp, Slack and Discord read Open Graph (og:title, og:description, og:image, og:url). X prefers its own twitter: tags but falls back to Open Graph for anything missing, so the only twitter tags most sites need are twitter:card and twitter:site. If you have no social tags at all, most platforms fall back again to the <title> and meta description — which is why some links preview with a title but no image.
Image rules that cause most blank previews
Use an absolute URL (https://…, never /img/share.png), keep it at 1200×630 or larger for a large card, stay under about 5 MB, and make sure it is publicly reachable — not behind a login, a staging password, or a hotlink block. Facebook and LinkedIn also cache aggressively: after fixing your tags you usually need to re-scrape the URL in the platform's own debugger before the new preview appears.
Text lengths for cards
Card titles are typically cut at around 60–70 characters and descriptions at 110–200 depending on the platform and screen. Front-load the meaningful words. A description that reads as a full sentence at 100 characters beats one that trails off mid-thought at 200.
Benefits
- Shows a Facebook/LinkedIn-style card and an X-style card side by side from your own tags.
- Flags missing tags, relative image URLs and over-long titles before you publish.
- Falls back the way real platforms do — page title and meta description when Open Graph is absent.
- No server involved, so you can test tags for a staging site that is not publicly reachable.
Limitations to know
- It cannot fetch a live URL, because browsers block cross-origin requests — you paste the tags instead.
- It cannot see the real image dimensions or file size, only whether the URL is absolute.
- Each platform renders cards slightly differently and changes them over time, so this is a close approximation.
Common mistakes to avoid
- Testing a fix without asking the platform to re-scrape, then assuming the tags are still wrong when the cached preview shows.
- Using an image smaller than 600×315, which most platforms downgrade to a small thumbnail.
- Duplicating every Open Graph tag with a twitter: equivalent, which adds bytes but changes nothing.
Alternatives
To write the tags in the first place, use the Meta Tag Generator. To produce a correctly sized share image, use the Image Resizer.
Last updated: August 2026 · Reviewed by the AI Toolbox editorial team.
Frequently asked questions
Can I just paste a URL?
No — browsers cannot fetch another site’s HTML because of the same-origin policy. View the page source and paste the head tags instead.
I fixed my tags but the old preview still shows. Why?
Platforms cache scraped previews. Use the official debugger for Facebook, LinkedIn or X and request a re-scrape of the URL.
Do I need both Open Graph and Twitter tags?
Usually not. X falls back to Open Graph, so twitter:card and twitter:site are normally the only extra tags worth adding.
What image size should I use?
1200×630 pixels is the safe default for a large card across every major platform. Below 600×315 most platforms downgrade to a small thumbnail.