Share a link with no OG tags → gray box with a bare URL. With them → image, title, description. For a site shared in student WhatsApp groups, this is free marketing.
The complete set
<meta property="og:title" content="CGPA Calculator — Anna University"> <meta property="og:description" content="Calculate GPA and CGPA instantly. Free."> <meta property="og:image" content="https://site.com/og-image.png"> <meta property="og:url" content="https://site.com/cgpa-calculator"> <meta property="og:type" content="website"> <meta name="twitter:card" content="summary_large_image">
The image rules
- 1200×630px — the universal size (WhatsApp, LinkedIn, X, Discord)
- Absolute URL required — relative paths silently fail
- Under ~300KB; text on it should be readable at thumbnail size
- No image budget? Generate one: your title on a brand-gradient background in Canva takes 5 minutes
Debugging previews
Platforms CACHE previews aggressively. After changes, force a refresh: LinkedIn Post Inspector, Facebook Sharing Debugger ("Scrape Again"), or add ?v=2 to the shared URL. Test in a self-DM on WhatsApp before posting to the group.