Website Category API: IAB Classification from a URL

A website category API takes a URL or domain and returns a content category you can store, target, or filter on. Klazify does that over REST: POST https://www.klazify.com/api/categorize with a Bearer token and {"url": "https://cbsnews.com"}. The JSON includes Klazify category paths, a confidence score from 0–1, logo, social profiles, and company firmographics in one call.

For ad-tech (brand safety, contextual targeting) use POST /api/domain_iab_categories. IAB keys sit inside each category object — V1 as IAB12, V3 as IAB-324-JLBCU7 — not in a nested IAB_categories hash. IAB Content Taxonomy v3 is 620+ nodes. Starter is $39.99/mo (500 successful calls, then $0.127968; 60 req/min) with a 7-day trial. Failed / unreachable calls are not billed. Docs: klazify.com/api-docs. Agents: MCP at mcp.klazify.com.

Request: categorize a URL

curl -X POST 'https://www.klazify.com/api/categorize' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"url": "https://cbsnews.com"}'

Every endpoint uses the same body shape except Discovery. Auth is Authorization: Bearer — not a query-string key.

Response: categories, logo, company (cbsnews.com)

Official All Together sample from the API docs (not a live recrawl):

{
  "domain": {
    "categories": [
      { "confidence": 0.97, "name": "/News" },
      { "confidence": 0.78, "name": "/Arts & Entertainment/TV & Video" }
    ],
    "domain_url": "https://cbsnews.com",
    "social_media": {
      "facebook_url": "https://facebook.com/CBSNews",
      "twitter_url": "https://twitter.com/CBSNews",
      "instagram_url": null,
      "youtube_url": "https://youtube.com/CBSNews"
    },
    "logo_url": "https://klazify.s3.amazonaws.com/..."
  },
  "success": true,
  "objects": {
    "company": {
      "name": "CBS News",
      "city": "New York",
      "stateCode": "NY",
      "countryCode": "US",
      "employeesRange": "1K-5K",
      "revenue": null,
      "raised": null,
      "tags": ["Publishing", "Broadcasting"],
      "tech": ["google_tag_manager", "salesforce"]
    }
  }
}

confidence of 1 is treated as an exact match. Multiple categories come back sorted by confidence descending. domain_url is the normalized host Klazify classified.

Request + response: IAB v1 and v3

curl -X POST 'https://www.klazify.com/api/domain_iab_categories' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{"url": "https://cbsnews.com"}'

Docs sample (updated_at 2026-07-30). V1 key IAB12 = News. V3 key IAB-324-JLBCU7 = Movies/Entertainment/Movies on the secondary path:

{
  "domain": {
    "categories": [
      {
        "confidence": 1,
        "name": "/News/Other",
        "IAB12": "News"
      },
      {
        "confidence": 0.28,
        "name": "/Arts & Entertainment/TV & Video/TV Networks & Stations",
        "IAB1": "Arts & Entertainment",
        "IAB-324-JLBCU7": "Movies/Entertainment/Movies"
      }
    ],
    "domain_url": "https://cbsnews.com",
    "updated_at": "2026-07-30T08:27:41.000000Z"
  },
  "success": true
}

Without refresh=true you get the cached IAB map. refresh=true recrawls the site and requires Advanced or above. Real-time Klazify paths (no cache) live on POST /api/real_time_categorization.

What you actually build with /api/categorize

Ad inventory. Store domain.categories[0].name (and IAB keys from the IAB endpoint) before you bid. Skip or down-rank paths you will not monetize.
CRM / lead lists. Firmographics in objects.company (name, city, employeesRange, tech) sit on the same categorize call — you do not need a second vendor for “what does this domain do.”
Logo in the UI. domain.logo_url is a hosted asset. Pair it with social_media when you render a publisher card.

Failed / unreachable calls are not billed on Klazify. Cache by normalized domain_url so a dashboard refresh does not burn the 500 Starter calls.

Go live

1. Register and start the 7-day trial.

2. Copy the Bearer key from the dashboard (same header on all 10 endpoints).

3. POST https://www.klazify.com/api/categorize with {"url":"https://cbsnews.com"}

4. Store domain.categories[0].name and, for ads, the sibling IAB* keys from /api/domain_iab_categories.

FAQ: website category API

What taxonomy does Klazify return?

Klazify paths such as /News on /api/categorize, plus IAB Content Taxonomy v1 and v3 keys on /api/domain_iab_categories. IAB IDs are sibling properties on each category item, not a separate object.

What does confidence 0.97 mean?

A decimal between 0 and 1. Higher is more certain; 1 is an exact match in the docs. CBS News in the sample is 0.97 on /News and 0.78 on TV & Video.

Is this the same as a Hub “website category” listing?

No. This classification API is Klazify (klazify.com), first-party. If you need IAB/URL classification, call Klazify — not a generic marketplace search.

Can an agent call it?

Yes. MCP tools include klazify.categorize → POST /api/categorize. Base URL https://mcp.klazify.com.

Start the 7-day trial and classify a URL →