OpenGraph deep-dive: og:image rules

The 5 OG tags (you saw 4 of these in A1; here's deep)

<meta property="og:title" content="Why FastAPI beats Flask in 2026" />
<meta property="og:description" content="Async-native, type-safe, production-grade. Here's the data." />
<meta property="og:image" content="https://example.com/og/why-fastapi.png" />
<meta property="og:image:width" content="1200" />
<meta property="og:image:height" content="630" />
<meta property="og:image:alt" content="A FastAPI logo over Python and Flask code samples" />
<meta property="og:url" content="https://example.com/blog/why-fastapi" />
<meta property="og:type" content="article" />
<meta property="og:site_name" content="CodeMentor AI" />
<meta property="article:published_time" content="2026-05-20T10:00:00Z" />
<meta property="article:author" content="Anna Kowalski" />

og:image — the make-or-break tag

• 1200 × 630 px — the universally-supported aspect ratio (1.91:1).
• Absolute URL. Same rule as canonical. /og.png doesn't work — must be full https://....
• < 5MB. Telegram caps at 5MB; some others lower.
• PNG or JPEG. WebP works on Telegram/Slack but NOT iMessage or LinkedIn (last I checked — verify).
• Critical text in central 1200×500. Some platforms crop the top/bottom ~65px.
• Include `og:image:alt`. Twitter/X reads it; some screen readers on shared cards use it.

og:type

Common values:

• website — landing pages, generic.
• article — blog posts. Unlocks article:published_time etc.
• product — e-commerce. Unlocks product:price:amount.
• video / music / book — media.

For an article, set og:type="article" and include published_time + author for richer cards.

Cache

OG cards are cached aggressively by platforms (Telegram caches 7-30 days). After publishing, paste the URL into the Telegram bot or Facebook Sharing Debugger to force a re-fetch.