Text Readability Score API

About the Text Readability Score API

Readability Score works by analyzing the text provided and calculating the readability score. It uses advanced algorithms to calculate the readability score based on various readability formulas and returns the readability score.

What people use it for

Editorial CMS Publishing

Before publishing articles, newsroom CMS editors check the Flesch-Kincaid grade level and word counts to match target reader expectations.

Patient Instructions Review

When clinicians draft care summaries, health portals flag passages scoring above an elementary target audience so staff can rephrase dense medical terms.

Curriculum Reading Assessment

To assign books to suitable grade bands, edtech apps evaluate uploaded chapters against Dale-Chall scores and the average grade level.

Consumer Contract Auditing

Flag convoluted policy clauses during drafting by checking consumer agreements against the Gunning Fog index and reading ease ratings.

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON

Default REST response

XML

Markup format

YAML

Human-readable

CSV

Tabular export

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — POST /v1/readabilityscore

Sent as JSON in the request body. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

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curl -X POST "https://api.apiverve.com/v1/readabilityscore" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":"Western astrology is founded on the movements and relative positions of celestial bodies such as the Sun, Moon and planets, which are analysed by their movement through signs of the zodiac (twelve spatial divisions of the ecliptic) and by their aspects (based on geometric angles) relative to one another."}'

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Response — POST /v1/readabilityscore

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

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{
  "status": "ok",
  "error": null,
  "data": {
    "textCounts": {
      "syllableCount": 82,
      "lexiconCount": 49,
      "sentenceCount": 1
    },
    "readability": {
      "fleschReadingEase": 13.28,
      "fleschKincaidGrade": 23.6,
      "gunningFog": 26.95,
      "colemanLiauIndex": 13.19,
      "smogIndex": 22.08,
      "automatedReadabilityIndex": 27.8,
      "daleChallReadabilityScore": 17
    },
    "readabilityText": {
      "fleschReadingEase": "very confusing",
      "daleChallReadabilityScore": "average 13th to 15th-grade (college) student"
    },
    "averageGradeLevel": 22.7,
    "targetAudience": "post-graduate"
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Zero-code embed — one snippet, no backend

Drop an interactive Text Readability Score form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.

Changelog — Text Readability Score API

Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.

Currently v1