Readability Checker API

Readability scores for English text (Flesch reading ease, Flesch–Kincaid grade, Gunning fog, SMOG, Coleman–Liau, ARI) plus counts of long sentences, passive voice, adverbs and complex words.

POST /api/v1/tools/readability-checkerMCP readability_checkerText & Writing

Score your writing with Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI, and highlight long sentences, passive voice and adverbs.

Input

Send these as a JSON object. Unknown fields are rejected.

input: The English text to analyse. (string, required)
segments: Also return each sentence with flags (long, passive, adverb, complex) for highlighting. (boolean, default false)

Try it in the browser JSON Schema Get an API key

curl https://pithlab.com/api/v1/tools/readability-checker \n  -H "Authorization: Bearer $PITHLAB_KEY" \n  -H "Content-Type: application/json" \n  -d '{"input":"The cat sat on the mat. It was a sunny day, and the birds were singing loudly in the tall trees."}'

Example response

{
  "ok": true,
  "result": {
    "sentences": 2,
    "words": 21,
    "syllables": 24,
    "letters": 73,
    "complexWords": 0,
    "longSentences": 0,
    "passive": 0,
    "adverbs": 1,
    "scores": {
      "fleschReadingEase": 99.49178571428574,
      "fleschKincaidGrade": 1.9907142857142865,
      "gunningFog": 4.2,
      "smog": 3.1291,
      "colemanLiau": 1.8209523809523809,
      "automatedReadabilityIndex": 0.19285714285714306
    },
    "averageGrade": 2.2667247619047624,
    "smogReliable": false,
    "readingEase": "Very easy"
  }
}