Paste the <head> of your page (View Source → copy from <head> to </head>). This lint checks the markup only and runs entirely in your browser — nothing is sent anywhere.
A markup lint can't tell you what a crawler actually received. The most common non-markup causes: the bot is blocked (Cloudflare Bot Fight Mode / WAF returning 403 to facebookexternalhit or LinkedInBot), the image URL redirects or 404s, the image is SVG/WebP-only or too large, or the platform is showing a cached preview (re-scrape in LinkedIn Post Inspector / Facebook Sharing Debugger).
To check those from the live URL, the free check at SharePack (linked in your results when the lint finds a problem) requests your page the way social bots do and shows what came back. Disclosure: I build SharePack. The free check is free; the optional $29 one-time repair pack generates the tags and a correctly sized image set for your page. It's not a design tool.
MIT · 9213651 Canada Inc. · idealstoronto@gmail.com · This page sets no cookies and loads no third-party scripts.