## What it does
Score the readability of any English text or URL. Returns 5 industry-standard readability scores, actionable plain-English suggestions, sentence-level breakdown with the hardest sentences flagged, and optional target grade pass/fail.
## Scores returned
- **Flesch Reading Ease** — 0–100. Higher = easier to read.
- **Flesch-Kincaid Grade** — US school grade equivalent.
- **Gunning Fog Index** — Years of education needed to understand.
- **Automated Readability Index (ARI)** — Grade level via character/word ratio.
- **SMOG Index** — Grade level via polysyllabic word density.
## Use cases
Content teams, legal/compliance, EdTech, SEO tools, CMS pipelines, A/B copy testing.
## Endpoints
- `POST /api/analyze` — analyse text or a URL, with optional target grade
- `POST /api/compare` — compare two texts side by side
{"success":true,"textStats":{"wordCount":18,"sentenceCount":2,"characterCount":85,"avgSentenceLength":9,"avgSyllablesPerWord":1.56,"polysyllabicWordCount":1,"polysyllabicWordPercentage":5.6},"scores":{"fleschReadingEase":{"score":66.1,"interpretation":"Standard","suitableFor":"Age 15–17"},"fleschKincaidGrade":{"score":6.3,"interpretation":"US Grade 6 reading level"},"gunningFog":{"score":5.8,"interpretation":"Very easy"},"automatedReadabilityIndex":{"score":5.3,"interpretation":"Roughly Grade 5 reading level"},"smogIndex":{"score":6.9,"interpretation":"Grade 7 reading level","note":"SMOG is most accurate with 30+ sentences"}},"overall":{"averageGradeLevel":6.1,"verdict":"Easy read","recommendedFor":"Most adults","plainEnglishScore":70},"suggestions":["Text is short (18 words). Readability scores are most reliable with 100+ words."],"sentenceBreakdown":{"all":[{"index":1,"sentence":"The quick brown fox jumps over the lazy dog.","wordCount":9,"fre":94.3,"grade":2.3,"complexity":"Easy"},{"index":2,"sentence":"This is a simple sentence for testing readability scores.","wordCount":9,"fre":37.9,"grade":10.2,"complexity":"Hard"}],"hardest":[{"index":2,"sentence":"This is a simple sentence for testing readability scores.","wordCount":9,"fre":37.9,"grade":10.2,"complexity":"Hard"},{"index":1,"sentence":"The quick brown fox jumps over the lazy dog.","wordCount":9,"fre":94.3,"grade":2.3,"complexity":"Easy"}]}}
curl --location --request POST 'https://zylalabs.com/api/12906/academic+readability+analysis+api/25689/analizar' --header 'Authorization: Bearer YOUR_API_KEY'
--data-raw '{"text": "The quick brown fox jumps over the lazy dog. This is a simple sentence for testing readability scores."}'
{"success":true,"text_a":{"fleschReadingEase":100,"gradeLevel":2.1,"verdict":"Very easy read","wordCount":11},"text_b":{"fleschReadingEase":0,"gradeLevel":19.4,"verdict":"Highly technical","wordCount":15},"comparison":{"moreReadable":"text_a","easeDifference":100,"gradeDifference":17.3,"summary":"text_a is easier to read by 100.0 Flesch points"}}
curl --location --request POST 'https://zylalabs.com/api/12906/academic+readability+analysis+api/25690/comparar' --header 'Authorization: Bearer YOUR_API_KEY'
--data-raw '{"text_a": "The cat sat on the mat. It was a sunny day.", "text_b": "The feline proceeded to position itself upon the horizontal surface whilst meteorological conditions remained favourable."}'
| Header | Description |
|---|---|
Authorization
|
[Required] Should be Bearer access_key. See "Your API Access Key" above when you are subscribed. |
No long-term commitment. Upgrade, downgrade, or cancel anytime. Free Trial includes up to 50 requests.
The `POST /api/analyze` endpoint returns readability scores, suggestions, sentence breakdowns, and an optional target grade result. The `POST /api/compare` endpoint provides a side-by-side comparison of two texts, including Flesch scores, grade levels, and readability verdicts.
Key fields include `wordCount`, `sentenceCount`, `scores` (like `fleschReadingEase` and `gunningFog`), `overall` (with `averageGradeLevel` and `verdict`), and `suggestions` for improvement. Each field provides insights into the text's readability.
The response data is structured in JSON format. For `POST /api/analyze`, it includes `textStats`, `scores`, `overall`, `suggestions`, and `sentenceBreakdown`. For `POST /api/compare`, it contains `text_a`, `text_b`, and `comparison` sections for easy readability assessment.
The `POST /api/analyze` endpoint accepts parameters such as the text or URL to analyze and an optional target grade for evaluation. The `POST /api/compare` endpoint requires two texts for comparison.
Users can customize requests by providing specific texts or URLs for analysis and setting a target grade level in the `POST /api/analyze` endpoint. This allows for tailored readability assessments based on user needs.
Typical use cases include content creation for clarity, legal document compliance, educational material development, SEO optimization, and A/B testing for marketing copy. The API helps ensure texts meet readability standards for their intended audience.
Data accuracy is maintained through the use of established readability formulas like Flesch and Gunning Fog, which are widely recognized in linguistic research. The API's algorithms are designed to provide consistent and reliable readability assessments.
Users can expect patterns such as higher Flesch Reading Ease scores indicating easier texts, while lower scores suggest complexity. Additionally, the average grade level will typically correlate with the readability scores, providing a clear understanding of text difficulty.
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