Skip to content
https://ndl.go.jp

Content

· 5 checks — Internal links, mixed-content guards, Open Graph previews, and structured data rolled into one auditable list.
SCORE
94
GRADE
A
FIX
0
REVIEW
2
PASS
3
INFO
0
Checks
5
3 PASS 2 REVIEW
C
Structured Data
Action
1 JSON-LD block(s) found — some improvements recommended.
REVIEW
1 JSON-LD block(s) found — some improvements recommended.
Critical::
Malformed JSON-LD block #1
JSON parse error: Mismatch type map[string]interface {} with value array "at index 0: mismatched type with value\n\n\t[{\"@context\":\"https://schema.org\n\t^...............................\n"

JSON parse error: Mismatch type map[string]interface {} with value array "at index 0: mismatched type with value\n\n\t[{\"@context\":\"https://schema.org\n\t^...............................\n"

Why this matters

JSON-LD block fails to parse — Google ignores the entire block, so structured data effectively isn't there.

Learn more ▾

Common causes: trailing comma, single quotes instead of double, unescaped quote in a string value. Validate at https://validator.schema.org/ or Search Console's Rich Results Test.

Source: schema.org / Google Search Central

JSON-LD Blocks

Block 1 : BreadcrumbList
0 properties Invalid
Invalid JSON: Mismatch type map[string]interface {} with value array "at index 0: mismatched type with value\n\n\t[{\"@context\":\"https://schema.org\n\t^...............................\n"
[
  {
    "@context": "https://schema.org",
    "@type": "BreadcrumbList",
    "itemListElement": [
      {
        "@type": "ListItem",
        "position": 1,
        "item": {
          "@id": "https://www.ndl.go.jp/",
          "name": "国立国会図書館"
        }
      }
    ]
  },
  {
    "@context": "https://schema.org",
    "@type": "WebSite",
    "name": "国立国会図書館",
    "url": "https://www.ndl.go.jp",
    "potentialAction": [
      {
        "@type": "SearchAction",
        "target": {
          "@type": "EntryPoint",
          "urlTemplate": "https://www.ndl.go.jp/search?cs=bib&f-ht=ndl&keyword={search_term_string}"
        },
        "query-input": "required name=search_term_string"
      }
    ]
  },
  {
    "@context": "https://schema.org",
    "@type": "Article",
    "headline": "トップページ",
    "datePublished": "2025-08-11T02:21:00.346Z+09:00"
  }
]
C
Brand Presence
Action
Site-name consistency, favicon, social image, meta tags, schema, and contact signals
REVIEW

Brand Presence

Partial brand coverage — a few channels are missing brand signals.

C

55/100

Site name appears as

Page title国立国会図書館
og:site_name国立国会図書館
twitter:site—
Organization.name—

Consistent

Brand assets

Favicon

12/15

covers apple-touch-icon

Social share image

14/20

og:image set; twitter:image missing

Meta completeness

14/20

Organization schema

0/15

Contact info discoverable

5/10

contact page

Findings

  • Missing brand name in: twitter:site, Organization.name
  • Add twitter:image — Twitter falls back to og:image only when it's larger than 300×157
  • Add an apple-touch-icon and at least two PNG sizes (32x32 + 192x192)
  • twitter:card missing
  • No Organization schema — Google can't render your logo in the knowledge panel
  • Only partial contact info discoverable — consider adding a dedicated contact page or mailto/tel link

How consistently your brand appears across channels — shared link previews, structured data, favicon, contact info.

A+
Mixed Content
No mixed content detected — all resources use HTTPS.
PASS
No mixed content detected — all resources use HTTPS.
Info::
No mixed content detected — all resources use HTTPS
A
Open Graph
Open Graph tags are well configured for social sharing.
PASS
Open Graph tags are well configured for social sharing.
Info::
og:title is short (7 characters)
Ideal length is 25–60 characters for social sharing previews.
Got: 7 chars Expected: 25–60 chars
Info::
Missing twitter:card
Without twitter:card, Twitter falls back to Open Graph tags. Adding it gives you more control.
URL: 7 chars

Ideal length is 25–60 characters for social sharing previews.

Expected: 25–60 chars
Why this matters

og:title very short — may render with awkward whitespace in social cards.

Source: Open Graph Protocol

Without twitter:card, Twitter falls back to Open Graph tags. Adding it gives you more control.

Why this matters

Without twitter:card, Twitter renders posts as plain text — no preview image, no structured layout.

Learn more ▾

Twitter requires `<meta name="twitter:card" content="summary_large_image">` (or summary) to render share-cards at all. Without it, links appear as raw text and engagement plummets vs cards. Twitter also falls back to og:image if twitter:image isn't set, so configure both.

Source: Twitter Developer Platform

Preview

ndl.go.jp

国立国会図書館

国立国会図書館の公式ウェブサイトです。当館は、国内外の資料・情報を広く収集・保存して、知識・文化の基盤となり、国会の活動を補佐するとともに、行政・司法及び国民に図書館サービスを提供しています。

Preview quality · Twitter/X F · 45/100

Description will be truncated (288 chars / 200 max)

  • twitter:card — Add <meta name="twitter:card" content="summary_large_image">
  • twitter:title — falling back from og:title
  • twitter:description — falling back from og:description
  • twitter:image — falling back from og:image

  • twitter:card is missing

    → Add <meta name="twitter:card" content="summary_large_image">

  • Description will be truncated on Twitter/X (288 chars, max 200)

    → Tighten the description to ≤200 characters

NDL.GO.JP

国立国会図書館

国立国会図書館の公式ウェブサイトです。当館は、国内外の資料・情報を広く収集・保存して、知識・文化の基盤となり、国会の活動を補佐するとともに、行政・司法及び国民に図書館サービスを提供しています。

Preview quality · Facebook A+ · 95/100

Description will be truncated (288 chars / 155 max)

  • og:title — 国立国会図書館
  • og:description — 国立国会図書館の公式ウェブサイトです。当館は、国内外の資料・情報を広く収集・保存して、知識・文化の基盤となり、国会の活動を補佐するとともに、行政・司法及び国民に図書館サービスを提供しています。
  • og:image — https://www.ndl.go.jp/assets/hp/og.png
  • og:type — article
  • og:url — https://www.ndl.go.jp/
  • og:site_name — 国立国会図書館

  • Description will be truncated on Facebook (288 chars, max 155)

    → Tighten og:description to ≤155 characters

国立国会図書館

ndl.go.jp

Preview quality · LinkedIn A+ · 95/100

Description will be truncated (288 chars / 150 max)

  • og:title — 国立国会図書館
  • og:description — 国立国会図書館の公式ウェブサイトです。当館は、国内外の資料・情報を広く収集・保存して、知識・文化の基盤となり、国会の活動を補佐するとともに、行政・司法及び国民に図書館サービスを提供しています。
  • og:image — https://www.ndl.go.jp/assets/hp/og.png

  • Description will be truncated on LinkedIn (288 chars, max 150)

    → Tighten og:description to ≤150 characters

ndl.go.jp

国立国会図書館

国立国会図書館の公式ウェブサイトです。当館は、国内外の資料・情報を広く収集・保存して、知識・文化の基盤となり、国会の活動を補佐するとともに、行政・司法及び国民に図書館サービスを提供しています。

Preview quality · Slack A+ · 100/100
  • og:title — 国立国会図書館
  • og:description — 国立国会図書館の公式ウェブサイトです。当館は、国内外の資料・情報を広く収集・保存して、知識・文化の基盤となり、国会の活動を補佐するとともに、行政・司法及び国民に図書館サービスを提供しています。
  • og:image — https://www.ndl.go.jp/assets/hp/og.png

Social preview quality

Averaged across Twitter/X, Facebook, LinkedIn, and Slack.

B · 83/100
FieldTwitter/XFacebookLinkedInSlack
og:title
og:description
og:image
og:type
og:url
og:site_name
twitter:card———
twitter:title⚠———
twitter:description⚠———
twitter:image⚠———
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback