Docs/APIs/Text Readability Score

Text Readability Score

Calculate readability score

OperationalCredits 1 per callp50 569msText ProcessingStar

Overview

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.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

POSThttps://api.apiverve.com/v1/readabilityscore
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 res = 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."
}),
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);
import requests

res = requests.post(
    "https://api.apiverve.com/v1/readabilityscore",
    headers={"x-api-key": "your_api_key_here"},
    json={
    "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."
},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])
package main

import (
	"fmt"
	"io"
	"net/http"
	"strings"
)

func main() {
	body := strings.NewReader(`{
  "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."
}`)
	req, _ := http.NewRequest("POST", "https://api.apiverve.com/v1/readabilityscore", body)
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

401 is the only auth verdict

A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.

Parameters

Sent as JSON in the request body. Premium parameters are accepted on every plan but only take effect on plans that include them.

ParameterTypeDescription
textRequiredstringThe text to calculate the readability score of

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

Sample 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 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.

FieldTypeExampleDescription
textCountsobject{...}
syllableCountnumber82
lexiconCountnumber49
sentenceCountnumber1
readabilityobject{...}
fleschReadingEasenumber13.28
fleschKincaidGradenumber23.6
gunningFognumber26.95
colemanLiauIndexnumber13.19
smogIndexnumber22.08
automatedReadabilityIndexnumber27.8
daleChallReadabilityScorenumber17
readabilityTextobject{...}
fleschReadingEasestring"very confusing"
daleChallReadabilityScorestring"average 13th to 15th-grade (college) student"
averageGradeLevelnumber22.7Average grade level from all metrics
targetAudiencestring"post-graduate"Suggested target audience based on readability

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

StatusMeaningWhat to do
400Input was rejectedRead error; it names the parameter.
401Key missing or invalidCheck the header name and the key value.
403Key valid, but not permittedA key restriction or IP allow-list; see key scoping.
429Rate limited, or out of creditsRead error to tell them apart; see rate limits.

Use cases

Content Analysis
Use the Readability Score API to calculate the readability score of text for content analysis. Use the data to analyze language, extract insights, and improve comprehension
Language Processing
Calculate readability score by using the Readability Score API for language processing. Use the data to analyze grammar, categorize text, and enhance understanding
Content Generation
Use the Readability Score API to calculate the readability score of text for content generation. Use the data to create variations, improve readability, and enhance engagement
Text Analysis
Calculate readability score by using the Readability Score API for text analysis. Use the data to analyze language, extract insights, and improve comprehension

Other ways to use Text Readability Score

Set up Text Readability Score on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKitReference →
Use it in Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.VerveSheetsReference →

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