Text Readability Score API

Overview

To use Text Readability Score, you need an API key. You can get one by creating a free account and visiting your dashboard.

POST Endpoint

https://api.apiverve.com/v1/readabilityscore

Example

How to call the Text Readability Score API in different programming languages.

curl -X POST \
  "https://api.apiverve.com/v1/readabilityscore" \
  -H "X-API-Key: your_api_key_here" \
  -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."
}'

const response = await fetch('https://api.apiverve.com/v1/readabilityscore', {
  method: 'POST',
  headers: {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    "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."
})
});

const data = await response.json();
console.log(data);

import requests

headers = {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
}

payload = {
    "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."
}

response = requests.post('https://api.apiverve.com/v1/readabilityscore', headers=headers, json=payload)

data = response.json()
print(data)

package main

import (
    "fmt"
    "io"
    "net/http"
    "bytes"
    "encoding/json"
)

func main() {
    payload := map[string]interface{}{
        "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."
    }

    jsonPayload, _ := json.Marshal(payload)
    req, _ := http.NewRequest("POST", "https://api.apiverve.com/v1/readabilityscore", bytes.NewBuffer(jsonPayload))

    req.Header.Set("X-API-Key", "your_api_key_here")
    req.Header.Set("Content-Type", "application/json")

    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    body, _ := io.ReadAll(resp.Body)
    fmt.Println(string(body))
}

{
  "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"
  }
}

Authentication

The Text Readability Score API requires authentication via API key. Include your API key in the request header:

X-API-Key: your_api_key_here

Learn more about authentication →

Interactive API Playground

Test the Text Readability Score API directly in your browser with live requests and responses.

Parameters

The following parameters are available for the Text Readability Score API:

Response

The Text Readability Score API returns responses in JSON, XML, YAML, and CSV formats. The JSON response is shown in the Example section above; alternative formats below.

Other Response Formats

<?xml version="1.0" encoding="UTF-8"?>
<response>
  <status>ok</status>
  <error xsi:nil="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
  <data>
    <textCounts>
      <syllableCount>82</syllableCount>
      <lexiconCount>49</lexiconCount>
      <sentenceCount>1</sentenceCount>
    </textCounts>
    <readability>
      <fleschReadingEase>13.28</fleschReadingEase>
      <fleschKincaidGrade>23.6</fleschKincaidGrade>
      <gunningFog>26.95</gunningFog>
      <colemanLiauIndex>13.19</colemanLiauIndex>
      <smogIndex>22.08</smogIndex>
      <automatedReadabilityIndex>27.8</automatedReadabilityIndex>
      <daleChallReadabilityScore>17</daleChallReadabilityScore>
    </readability>
    <readabilityText>
      <fleschReadingEase>very confusing</fleschReadingEase>
      <daleChallReadabilityScore>average 13th to 15th-grade (college) student</daleChallReadabilityScore>
    </readabilityText>
    <averageGradeLevel>22.7</averageGradeLevel>
    <targetAudience>post-graduate</targetAudience>
  </data>
</response>

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 Structure

All API responses follow a consistent structure with the following fields:

Learn more about response formats →

Response Data Fields

When the request is successful, the data object contains the following fields:

Headers

Only X-API-Key is required. Optional headers include Accept for response format negotiation (JSON, XML, or YAML), User-Agent, and X-Request-ID for request tracing. See all request headers →

GraphQL AccessALPHA

Access Text Readability Score through GraphQL to combine it with other API calls in a single request. Query only the text readability score data you need with precise field selection, and orchestrate complex data fetching workflows.

Credit Cost: Each API called in your GraphQL query consumes its standard credit cost.

POST https://api.apiverve.com/v1/graphql

query {
  readabilityscore(
    input: {
      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."
    }
  ) {
    textCounts {
      syllableCount
      lexiconCount
      sentenceCount
    }
    readability {
      fleschReadingEase
      fleschKincaidGrade
      gunningFog
      colemanLiauIndex
      smogIndex
      automatedReadabilityIndex
      daleChallReadabilityScore
    }
    readabilityText {
      fleschReadingEase
      daleChallReadabilityScore
    }
    averageGradeLevel
    targetAudience
  }
}

Note: Authentication is handled via the x-api-key header in your GraphQL request, not as a query parameter.

CORS Support

The Text Readability Score API accepts cross-origin requests from any origin, so it can be called directly from browser-based applications without a proxy. See CORS support →

Rate Limiting

Text Readability Score requests are throttled per minute on the Free plan and unthrottled on paid plans. Exceeding the limit returns 429 Too Many Requests; rate-limit usage is reported in the X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset response headers. See per-plan limits and best practices →

Error Codes

The Text Readability Score API uses standard HTTP status codes — 200 on success, 400 for invalid parameters, 401 for missing or invalid keys, 403 for insufficient credits, 429 for rate-limit exhaustion, and 500/503 for server-side issues. Each error response includes an X-Request-ID header you can quote when contacting support. See full error handling guide →

SDKs for Text Readability Score

Official Text Readability Score packages on npm, PyPI, NuGet, and JitPack — plus a Postman collection and an OpenAPI spec. See the SDK guide →

JitPack

No-Code Integrations

Text Readability Score works with Zapier, Make, Pipedream, n8n, and Power Automate using the same API key. See setup guides →

Zapier

Make

Pipedream

n8n

Power Automate

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