HTML Validator — inspect structured data in HTML

Validate HTML API

What it does

HTML Validator checks a page’s markup for structured data and related SEO signals. Send raw HTML in the html field, and get back the detected structured-data and metadata objects the page exposes.

Use it to audit pages before release, spot missing or malformed schema markup, and confirm that search engines can read the signals you intend to publish. The response includes the page url when available, plus json_ld, microdata, meta_tags, open_graph, and twitter_card data extracted from the HTML.

The summary object gives you a quick read on what was found: warnings, critical_errors, overall_score, total_entities, types_found, and rich_results_eligible. That makes it useful for automated QA in CI, content checks in CMS workflows, or bulk review of landing pages after template changes.

If you work on technical SEO or structured data, HTML Validator gives you a compact way to inspect what’s actually present in the document without parsing it yourself.

Quickstart

Send the HTML you want to validate as a JSON body.

curl -X POST "http://localhost:8080/chisleroff/validate-html" \
  -H "apy-token: $APY_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"html":"<!doctype html><html><head><title>Example</title></head><body><h1>Hello world</h1></body></html>"}'

What you'll get back

Returns a JSON object with these top-level fields when present: url and source_url are strings, json_ld, microdata are arrays of objects, meta_tags, open_graph, and twitter_card are objects, and summary is an object with warnings and critical_errors integers, overall_score as a number, total_entities as an integer, and types_found and rich_results_eligible as arrays of strings.

{
  "url": "https://example.com/page",
  "json_ld": [],
  "summary": {
    "warnings": 0,
    "types_found": [],
    "overall_score": 0,
    "total_entities": 0,
    "critical_errors": 0,
    "rich_results_eligible": []
  },
  "meta_tags": {},
  "microdata": [],
  "open_graph": {},
  "source_url": "https://example.com/page",
  "twitter_card": {}
}

About this endpoint

What it does

Validates the structured data found in raw HTML content. It accepts an HTML string in the request body and returns the extracted structured-data-related artifacts and summary information found in the page.

Request Body

Parameter	Type	Mandatory	Description
html	String	Yes	Raw HTML content to validate for structured data. Maximum length: 5,000,000 characters.

Response

Returns a JSON object with these top-level fields: url string, json_ld array of objects, summary object, meta_tags object, microdata array of objects, open_graph object, source_url string, and twitter_card object.

Parameter	Type	Mandatory	Description
url	String	No	The URL associated with the validated HTML, if provided in the response.
json_ld	Object Array	No	JSON-LD objects extracted from the HTML. Each item is an object that may contain additional properties.
summary	Object	No	Validation summary information. Contains the following fields: `warnings` integer, `types_found` string array, `overall_score` number, `total_entities` integer, `critical_errors` integer, and `rich_results_eligible` string array.
meta_tags	Object	No	Meta tag data extracted from the HTML. The object may contain additional properties.
microdata	Object Array	No	Microdata objects extracted from the HTML. Each item is an object that may contain additional properties.
open_graph	Object	No	Open Graph data extracted from the HTML. The object may contain additional properties.
source_url	String	No	The source URL associated with the HTML, if provided in the response.
twitter_card	Object	No	Twitter card data extracted from the HTML. The object may contain additional properties.

Body

Name

Type

Description

bodyREQUIRED

object

—

Quickstart

What you'll get back

About this endpoint

What it does

Request Body

Response

Body

Errors any endpoint can return