Text Readability ScoreText Readability Score API

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Readability Score is a simple tool for calculating the readability score of text. It returns the readability score based on various readability formulas.

The Text Readability Score API provides reliable and fast access to text readability score data through a simple REST interface. Built for developers who need consistent, high-quality results with minimal setup time.

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

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

Code Examples

Here are examples of how to call the Text Readability Score API in different programming languages:

cURL Request
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."
}'
JavaScript (Fetch API)
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);
Python (Requests)
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)
Node.js (Native HTTPS)
const https = require('https');
const url = require('url');

const options = {
  method: 'POST',
  headers: {
    'X-API-Key': 'your_api_key_here',
    'Content-Type': 'application/json'
  }
};

const postData = 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 req = https.request('https://api.apiverve.com/v1/readabilityscore', options, (res) => {
  let data = '';
  res.on('data', (chunk) => data += chunk);
  res.on('end', () => console.log(JSON.parse(data)));
});

req.write(postData);
req.end();
PHP (cURL)
<?php

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, 'https://api.apiverve.com/v1/readabilityscore');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'X-API-Key: your_api_key_here',
    'Content-Type: application/json'
]);

curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode({
    '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.'
}));

$response = curl_exec($ch);
curl_close($ch);

$data = json_decode($response, true);
print_r($data);

?>
Go (net/http)
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))
}
Ruby (Net::HTTP)
require 'net/http'
require 'json'

uri = URI('https://api.apiverve.com/v1/readabilityscore')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true

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."
}

request = Net::HTTP::Post.new(uri)
request['X-API-Key'] = 'your_api_key_here'
request['Content-Type'] = 'application/json'

request.body = payload.to_json

response = http.request(request)
puts JSON.pretty_generate(JSON.parse(response.body))
C# (HttpClient)
using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        using var client = new HttpClient();
        client.DefaultRequestHeaders.Add("X-API-Key", "your_api_key_here");

        var jsonContent = @"{
        ""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.""
}";
        var content = new StringContent(jsonContent, Encoding.UTF8, "application/json");

        var response = await client.PostAsync("https://api.apiverve.com/v1/readabilityscore", content);
        response.EnsureSuccessStatusCode();

        var responseBody = await response.Content.ReadAsStringAsync();
        Console.WriteLine(responseBody);
    }
}

Authentication

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

Required 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:

Calculate Readability Score

ParameterTypeRequiredDescriptionDefaultExample
textstringrequired
The text to calculate the readability score of
-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

The Text Readability Score API returns responses in JSON, XML, YAML, and CSV formats:

Example Responses

JSON Response
200 OK
{
  "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"
  }
}
XML Response
200 OK
<?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>
YAML Response
200 OK
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
CSV Response
200 OK
keyvalue
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}
averageGradeLevel22.7
targetAudiencepost-graduate

Response Structure

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

FieldTypeDescriptionExample
statusstringIndicates whether the request was successful ("ok") or failed ("error")ok
errorstring | nullContains error message if status is "error", otherwise nullnull
dataobject | nullContains the API response data if successful, otherwise null{...}

Learn more about response formats →

Response Data Fields

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

Response fields marked with Premium are available exclusively on paid plans.View pricing
FieldTypeSample ValueDescription
textCountsobject{...}-
â”” syllableCountnumber82-
â”” lexiconCountnumber49-
â”” sentenceCountnumber1-
readabilityobject{...}-
â”” fleschReadingEasenumber13.28-
â”” fleschKincaidGradenumber23.6-
â”” gunningFognumber26.95-
â”” colemanLiauIndexnumber13.19-
â”” smogIndexnumber22.08-
â”” automatedReadabilityIndexnumber27.8-
â”” daleChallReadabilityScorenumber17-
readabilityTextobject{...}-
â”” fleschReadingEasestring"very confusing"-
â”” daleChallReadabilityScorestring"average 13th to 15th-grade (college) student"-
averageGradeLevelPremiumnumber22.7Average grade level from all metrics
targetAudiencePremiumstring"post-graduate"Suggested target audience based on readability

Headers

Required and optional headers for Text Readability Score API requests:

Header NameRequiredExample ValueDescription
X-API-Keyrequiredyour_api_key_hereYour APIVerve API key. Found in your dashboard under API Keys.
Acceptoptionalapplication/jsonSpecify response format: application/json (default), application/xml, or application/yaml
User-AgentoptionalMyApp/1.0Identifies your application for analytics and debugging purposes
X-Request-IDoptionalreq_123456789Custom request identifier for tracking and debugging requests
Cache-Controloptionalno-cacheControl caching behavior for the request and response

Learn more about 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.

Test Text Readability Score in the GraphQL Explorer to confirm availability and experiment with queries.

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

GraphQL Endpoint
POST https://api.apiverve.com/v1/graphql
GraphQL Query Example
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 supports Cross-Origin Resource Sharing (CORS) with wildcard configuration, allowing you to call Text Readability Score directly from browser-based applications without proxy servers.

CORS HeaderValueDescription
Access-Control-Allow-Origin*Accepts requests from any origin
Access-Control-Allow-Methods*Accepts any HTTP method
Access-Control-Allow-Headers*Accepts any request headers

Browser Usage: You can call Text Readability Score directly from JavaScript running in the browser without encountering CORS errors. No proxy server or additional configuration needed.

Learn more about CORS support →

Rate Limiting

Text Readability Score API requests are subject to rate limiting based on your subscription plan. These limits ensure fair usage and maintain service quality for all Text Readability Score users.

PlanRate LimitDescription
Free5 requests/minHard rate limit enforced - exceeding will return 429 errors
StarterNo LimitProduction ready - standard traffic priority
ProNo LimitProduction ready - preferred traffic priority
MegaNo LimitProduction ready - highest traffic priority

Learn more about rate limiting →

Rate Limit Headers

When rate limits apply, each Text Readability Score response includes headers to help you track your usage:

HeaderDescription
X-RateLimit-LimitMaximum number of requests allowed per time window
X-RateLimit-RemainingNumber of requests remaining in the current window
X-RateLimit-ResetUnix timestamp when the rate limit window resets

Handling Rate Limits

Free Plan: When you exceed your rate limit, Text Readability Score returns a 429 Too Many Requests status code. Your application should implement appropriate backoff logic to handle this gracefully.

Paid Plans: No rate limiting or throttling applied. All paid plans (Starter, Pro, Mega) are production-ready.

Best Practices for Text Readability Score:

  • Monitor the rate limit headers to track your Text Readability Score usage (Free plan only)
  • Cache text readability score responses where appropriate to reduce API calls
  • Upgrade to Pro or Mega for guaranteed no-throttle Text Readability Score performance

Note: Text Readability Score rate limits are separate from credit consumption. You may have credits remaining but still hit rate limits when using Text Readability Score on Free tier.

Error Codes

The Text Readability Score API uses standard HTTP status codes to indicate success or failure:

CodeMessageDescriptionSolution
200OKRequest successful, data returnedNo action needed - request was successful
400Bad RequestInvalid request parameters or malformed requestCheck required parameters and ensure values match expected formats
401UnauthorizedMissing or invalid API keyInclude x-api-key header with valid API key from dashboard
403ForbiddenAPI key lacks permission or insufficient creditsCheck credit balance in dashboard or upgrade plan
429Too Many RequestsRate limit exceeded (Free: 5 req/min)Implement request throttling or upgrade to paid plan
500Internal Server ErrorServer error occurredRetry request after a few seconds, contact support if persists
503Service UnavailableAPI temporarily unavailableWait and retry, check status page for maintenance updates

Learn more about error handling →

Need help? Contact support with your X-Request-ID for assistance.

Integrate Text Readability Score with SDKs

Get started quickly with official Text Readability Score SDKs for your preferred language. Each library handles authentication, request formatting, and error handling automatically.

Available for Node.js, Python, C#/.NET, and Android/Java. All SDKs are open source and regularly updated.

Integrate Text Readability Score with No-Code API Tools

Connect the Text Readability Score API to your favorite automation platform without writing code. Build workflows that leverage text readability score data across thousands of apps.

All platforms use your same API key to access Text Readability Score. Visit our integrations hub for step-by-step setup guides.

Frequently Asked Questions

How do I get an API key for Text Readability Score?
Sign up for a free account at dashboard.apiverve.com. Your API key will be automatically generated and available in your dashboard. The same key works for Text Readability Score and all other APIVerve APIs. The free plan includes 1,000 credits plus a 500 credit bonus.
How many credits does Text Readability Score cost?

Each successful Text Readability Score API call consumes credits based on plan tier. Check the pricing section above for the exact credit cost. Failed requests and errors don't consume credits, so you only pay for successful text readability score lookups.

Can I use Text Readability Score in production?

The free plan is for testing and development only. For production use of Text Readability Score, upgrade to a paid plan (Starter, Pro, or Mega) which includes commercial use rights, no attribution requirements, and guaranteed uptime SLAs. All paid plans are production-ready.

Can I use Text Readability Score from a browser?
Yes! The Text Readability Score API supports CORS with wildcard configuration, so you can call it directly from browser-based JavaScript without needing a proxy server. See the CORS section above for details.
What happens if I exceed my Text Readability Score credit limit?

When you reach your monthly credit limit, Text Readability Score API requests will return an error until you upgrade your plan or wait for the next billing cycle. You'll receive notifications at 80% and 95% usage to give you time to upgrade if needed.

What's Next?

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