Website Readability API

POST

Score the reading difficulty and grade level of any web page.

Website Readability analyzes live web pages to score their reading difficulty and educational grade level. It returns Flesch Reading Ease, Flesch-Kincaid grade level, word count, sentence count, and estimated reading time.

Try it — live request, no key required

Request

POSTapi.apiverve.com/v1/websitereadability

Body

urlstring

Verification

Format

No key required to try it. Get a key to use it in your app.

Example

{
  "status": "ok",
  "error": null,
  "data": {
    "fleschReadingEase": 24.34,
    "fleschReadingEaseText": "Very Confusing",
    "fleschKincaidGrade": 19.3,
    "gunningFog": 19.62,
    "colemanLiauIndex": 13.12,
    "smogIndex": 14.37,
    "automatedReadabilityIndex": 22.6,
    "daleChallReadabilityScore": 17,
    "daleChallReadabilityScoreText": "average 13th to 15th-grade (college) student",
    "wordCount": 634,
    "sentenceCount": 29,
    "readingTimeMinutes": 3,
    "averageGradeLevel": 17.8,
    "targetAudience": "post-graduate",
    "url": "https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts"
  }
}

About the Website Readability API

Website Readability works by fetching the page, extracting its readable text and scoring it across standard readability indices (Flesch, Gunning Fog, SMOG, Coleman-Liau, ARI, Dale-Chall). It also reports the word and sentence counts, an estimated reading time, an averaged grade level and the target reader audience so you can judge a page's accessibility at a glance.

What people use it for

Content Management Audits: CMS plugins check published articles against Flesch-Kincaid grade scores to keep drafts within target reading levels before publication.
Public Notice Compliance: When updating government web portals, compliance teams verify that policy notices maintain high Flesch Reading Ease scores for clear public comprehension.
EdTech Article Recommendation: Educational platforms inspect external articles by URL to pair students with texts matching their current reading grade and estimated reading time.
Search Content Optimization: Flag overly dense blog posts during site audits by tracking reading ease scores and sentence counts against top-ranking search competitors.

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
GraphQL: Query language
MCP: For AI agents

View all integrations →

Questions.

Common questions about the Website Readability API.

Read the docs →

Which plan fits 10,000 readability checks a month?

The Starter plan easily covers that volume. Each check costs 10 credits, so 10,000 checks use 100,000 of the Starter plan's 200,000 monthly credits, which works out to about $1.50 per 1,000 calls. The Free plan includes 20 checks every month for evaluation.

Are the Gunning Fog score and target audience ratings included on the Free plan?

No, advanced indices and reader audience classifications require a paid plan. The Free plan returns the Flesch Reading Ease score, Flesch-Kincaid Grade Level, word count, sentence count, and reading time. Upgrading to Starter or above unlocks Gunning Fog, SMOG, Coleman-Liau, ARI, Dale-Chall scores, the average grade level, and the target audience tag.

Which readability metrics are calculated for each page?

The API calculates Flesch Reading Ease and Flesch-Kincaid Grade Level on every plan; paid plans add Gunning Fog, Coleman-Liau Index, SMOG Index, Automated Readability Index, and Dale-Chall Readability Score. It also provides word count, sentence count, estimated reading time in minutes based on 238 words per minute, and a consolidated average grade level on paid plans.

Does the analysis run against the live website content?

Yes. Every request fetches the specified URL in real time, extracts the readable text directly from the page, and calculates the readability formulas immediately.

How does the API determine reading time?

Reading time is calculated directly from the extracted word count using a standard adult reading benchmark of 238 words per minute. The response returns this estimate in fractional minutes alongside the total word and sentence counts.

Request parameters — POST /v1/websitereadability

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

Parameter	Type	Example	Description
`url`Required	string	`https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts`	The URL of the web page to analyze url

Example request

curl -X POST "https://api.apiverve.com/v1/websitereadability" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts"}'

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.

Header	When	Value
`x-api-key`Required	Every request	Your API key. Header names are case-insensitive, so `X-API-Key` is the same header.
`Authorization`Alternate	Instead of the above	`Bearer <key>` — for clients that only expose bearer auth. Resolves to the same account and the same billing.
`content-type`Required	POST body	`application/json`

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.

Response — POST /v1/websitereadability

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.

Sample response

{
  "status": "ok",
  "error": null,
  "data": {
    "fleschReadingEase": 24.34,
    "fleschReadingEaseText": "Very Confusing",
    "fleschKincaidGrade": 19.3,
    "gunningFog": 19.62,
    "colemanLiauIndex": 13.12,
    "smogIndex": 14.37,
    "automatedReadabilityIndex": 22.6,
    "daleChallReadabilityScore": 17,
    "daleChallReadabilityScoreText": "average 13th to 15th-grade (college) student",
    "wordCount": 634,
    "sentenceCount": 29,
    "readingTimeMinutes": 3,
    "averageGradeLevel": 17.8,
    "targetAudience": "post-graduate",
    "url": "https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts"
  }
}

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.

Field	Type	Example	Description
`fleschReadingEase`	number	`24.34`	Flesch Reading Ease score (0-100, higher is easier)
`fleschReadingEaseText`	string	`"Very Confusing"`	Descriptive text interpretation of Flesch Reading Ease
`fleschKincaidGrade`	number	`19.3`	Flesch-Kincaid Grade Level (US school grade equivalency)
`gunningFog`Premium	number	`19.62`	Gunning Fog Index (years of education needed to understand)
`colemanLiauIndex`Premium	number	`13.12`	Coleman-Liau Index (US grade level based on character count)
`smogIndex`Premium	number	`14.37`	SMOG Index (years of education to understand text)
`automatedReadabilityIndex`Premium	number	`22.6`	Automated Readability Index (US grade level estimate)
`daleChallReadabilityScore`Premium	number	`17`	Dale-Chall Readability Score (educational level)
`daleChallReadabilityScoreText`Premium	string	`"average 13th to 15th-grade (college) student"`	Descriptive interpretation of Dale-Chall Readability Score
`wordCount`	number	`634`	Number of words in the page's readable text
`sentenceCount`	number	`29`	Number of sentences in the page's readable text
`readingTimeMinutes`	number	`3`	Estimated reading time in minutes at an average adult reading speed of 238 words per minute
`averageGradeLevel`Premium	number	`17.8`	Single averaged US school grade level digested from the grade-based indices (Flesch-Kincaid, Gunning Fog, Coleman-Liau, SMOG, ARI) — the one number that summarizes how much education a reader needs
`targetAudience`Premium	string	`"post-graduate"`	Reader band mapped from the average grade level: elementary, middle school, high school, college, post-graduate or general public
`url`	string	`"https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/concepts"`	The analyzed URL from the request

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.

Header	What it carries
`x-api-remaining-credits`	Credits left in the current cycle
`x-api-credits-used`	Credits spent in the current cycle
`x-api-max-credits`	The allowance for the cycle
`x-api-version`	Version of the endpoint that answered

Errors

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

Status	Meaning	What to do
`400`	Input was rejected	Read `error`; it names the parameter that has to change.
`401`	Key missing or invalid	Check the header name and the key value.
`403`	Key valid, but not permitted here	A key restriction or an IP allow-list — never a bad key.
`429`	Rate limited, or out of credits	Read `error` to tell them apart, then back off or top up.

What a call costs — 10 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.

Plan	Per month	Credits	Website Readability calls	Per 1,000 calls
Free	Free	200	20	Free
Starter	$29.99	200,000	20,000	$1.50
Pro	$99.99	1,000,000	100,000	$1.00
Mega	$299.99	4,000,000	400,000	$0.75

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.

Compare all pricing tiers →

Call it from cURL — POST /v1/websitereadability

No SDK to install — this is a plain HTTPS call to /v1/websitereadability with your key in the x-api-key header. Swap in a real key and it runs as-is.

cURL

1
2

curl "https://api.apiverve.com/v1/websitereadability" \
  -H "x-api-key: YOUR_API_KEY"

Resources

GitHubapiverve/websitereadability-apiSource, issues and the examples this page is built from.ReferenceWebsite Readability API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/websitereadabilitynpm apiverve-websitereadabilityPyPI APIVerve.API.WebsiteReadabilityNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Node.js — POST /v1/websitereadability

Install the Node.js SDK, then call the Website Readability API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — npm

npm install @apiverve/websitereadability

Node.js

const res = await fetch("https://api.apiverve.com/v1/websitereadability", {
  headers: { "x-api-key": "YOUR_API_KEY" },
});
const { data } = await res.json();
console.log(data);

Resources

npm@apiverve/websitereadabilityThe published Node.js client, versioned and signed.GitHubapiverve/websitereadability-apiSource, issues and the examples this page is built from.ReferenceWebsite Readability API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

apiverve-websitereadabilityPyPI APIVerve.API.WebsiteReadabilityNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Python — POST /v1/websitereadability

Install the Python SDK, then call the Website Readability API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — PyPI

pip install apiverve-websitereadability

Python

import requests

res = requests.get(
    "https://api.apiverve.com/v1/websitereadability",
    headers={"x-api-key": "YOUR_API_KEY"},
)
print(res.json()["data"])

Resources

PyPIapiverve-websitereadabilityThe published Python client, versioned and signed.GitHubapiverve/websitereadability-apiSource, issues and the examples this page is built from.ReferenceWebsite Readability API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/websitereadabilitynpm APIVerve.API.WebsiteReadabilityNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from C# / .NET — POST /v1/websitereadability

Install the C# / .NET SDK, then call the Website Readability API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — NuGet

dotnet add package APIVerve.API.WebsiteReadability

C# / .NET

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");

var json = await client.GetStringAsync("https://api.apiverve.com/v1/websitereadability");
Console.WriteLine(json);

Resources

NuGetAPIVerve.API.WebsiteReadabilityThe published C# / .NET client, versioned and signed.GitHubapiverve/websitereadability-apiSource, issues and the examples this page is built from.ReferenceWebsite Readability API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/websitereadabilitynpm apiverve-websitereadabilityPyPI

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Go — POST /v1/websitereadability

No SDK to install — this is a plain HTTPS call to /v1/websitereadability with your key in the x-api-key header. Swap in a real key and it runs as-is.

req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/websitereadability", nil)
req.Header.Set("x-api-key", "YOUR_API_KEY")

res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))

Resources

Also published for

@apiverve/websitereadabilitynpm apiverve-websitereadabilityPyPI APIVerve.API.WebsiteReadabilityNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from PHP — POST /v1/websitereadability

No SDK to install — this is a plain HTTPS call to /v1/websitereadability with your key in the x-api-key header. Swap in a real key and it runs as-is.

PHP

$ch = curl_init("https://api.apiverve.com/v1/websitereadability");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-api-key: YOUR_API_KEY"]);

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

Resources

Also published for

@apiverve/websitereadabilitynpm apiverve-websitereadabilityPyPI APIVerve.API.WebsiteReadabilityNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Ruby — POST /v1/websitereadability

No SDK to install — this is a plain HTTPS call to /v1/websitereadability with your key in the x-api-key header. Swap in a real key and it runs as-is.

Ruby

require "net/http"

uri = URI("https://api.apiverve.com/v1/websitereadability")
req = Net::HTTP::Get.new(uri)
req["x-api-key"] = "YOUR_API_KEY"

res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
puts res.body

Resources

Also published for

@apiverve/websitereadabilitynpm apiverve-websitereadabilityPyPI APIVerve.API.WebsiteReadabilityNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

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Website Readability API

Try it — live request, no key required

About the Website Readability API

What people use it for

Ways to call it

Other ways to use Website Readability

Questions.

Request parameters — POST /v1/websitereadability

Required

Authentication

Response — POST /v1/websitereadability

Response fields

Response headers

Errors

What a call costs — 10 credits per call

Call it from cURL — POST /v1/websitereadability

Resources

Also published for

Call it from Node.js — POST /v1/websitereadability

Resources

Also published for

Call it from Python — POST /v1/websitereadability

Resources

Also published for

Call it from C# / .NET — POST /v1/websitereadability

Resources

Also published for

Call it from Go — POST /v1/websitereadability

Resources

Also published for

Call it from PHP — POST /v1/websitereadability

Resources

Also published for

Call it from Ruby — POST /v1/websitereadability

Resources

Also published for

Zero-code embed — one snippet, no backend

Changelog — Website Readability API

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