A practical checklist to make thumbnails render correctly on KakaoTalk, Naver, Facebook, and X.
1. The 5 essential tags
<meta property="og:title" content="Page title" />
<meta property="og:description" content="Summary under 100 chars" />
<meta property="og:image" content="https://example.com/og.png" />
<meta property="og:url" content="https://example.com/article" />
<meta property="og:type" content="website" />
2. og:image specs
- Resolution: 1200×630 recommended (1.91:1). 600×315 minimum.
- Size: under 8MB. KakaoTalk often fails above 5MB.
- Format: PNG or JPG. WebP is unreliable on KakaoTalk.
- Filename: ASCII + dashes. Non-ASCII filenames break on FB/Kakao.
- HTTPS required: most platforms reject HTTP images.
3. KakaoTalk tips
- Cache is sticky (2–3 hours). If your change does not reflect, that is expected.
- Force refresh via Kakao Debugger.
- Large-card conditions: og:image width ≥ 600px, og:title + og:description both set, image publicly reachable.
4. Naver Blog / Cafe
- Naver parses only a subset of OG and also picks the first body image.
- Square (1:1) images look cleanest on Naver search/blog list.
- Allow
Yeti and Daumoa in robots.txt.
5. Facebook / X
- Facebook Sharing Debugger → "Scrape Again" for instant refresh.
- Set
twitter:card=summary_large_image for big cards on X. - X falls back to og:image if twitter:image is missing.
6. Common breakage patterns
- Vercel/Cloudflare preview domains set og:url to the canonical host → cache key conflicts.
- SPA (React/Vue) with empty initial HTML → needs SSR or prerender.
- og:image with query string → KakaoTalk may mis-key the cache.
- Signed CDN URLs expire → thumbnails break a few days later.
7. Debug order
- Scan with this tool first (which tags are missing).
- FB Sharing Debugger — verify image fetch over HTTPS.
- Kakao Debugger — force cache refresh.
- Paste the link into an actual KakaoTalk chat to eyeball.