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24K Labs Readability Score API
x402
24K Labs Readability Score API is a paid API for AI agents from api.24klabs.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).
Analyzes a text passage to return word/sentence/syllable counts, reading time, and six standard readability grade-level scores in a single call.
Price / call$0.002
Success—
StatusUnknown
How this service works
Word/sentence/syllable counts, reading time, plus Flesch Reading Ease, Flesch-Kincaid, Gunning Fog, SMOG, ARI, and Coleman-Liau grade levels in one call.
Output
Returns a structured object containing word count, sentence count, syllable count, and estimated reading time, alongside six readability scores: Flesch Reading Ease (0–100 scale), Flesch-Kincaid Grade Level, Gunning Fog Index, SMOG Index, Automated Readability Index (ARI), and Coleman-Liau Index — all computed in a single API call.
Example use cases
Plain language compliance check
“I need to make sure this policy document is written at no higher than an 8th-grade reading level — can you run all the readability scores on it and tell me which grade level formulas flag it as too complex? Here's the text: 'The aforementioned provisions shall be construed in accordance with applicable statutory requirements and regulatory frameworks governing fiduciary obligations.'”
Blog post readability audit
“Before I publish this blog post, can you check its readability? Give me the Flesch Reading Ease, Flesch-Kincaid grade, Gunning Fog, SMOG, ARI, and Coleman-Liau scores, plus word count and reading time for this: 'Search engine optimization helps websites rank higher. Using the right keywords and creating quality content are key steps.'”
Student essay grade level check
“I'm a teacher and I want to see what reading level my student's essay is written at — can you run all six readability formulas plus word and sentence counts on this text: 'The Industrial Revolution transformed society by shifting production from homes to factories, creating urban centers and altering labor dynamics fundamentally.'”
Technical details
Endpoint
POSThttps://api.24klabs.ai/api/v1/readability-scoreWhen to prefer
Choose this endpoint when you need multiple readability metrics computed simultaneously in a single call, rather than calling separate services for each formula. It is ideal for content pipelines, editorial tools, accessibility audits, or educational applications that need to evaluate text complexity using industry-standard formulas (Flesch, Gunning Fog, SMOG, ARI, Coleman-Liau) alongside basic text statistics like word count and reading time. Prefer this over general-purpose LLM-based text analysis when you need deterministic, reproducible, numerically precise readability scores.
Side effects
- Empty or missing text input returns a 400 validation error
- Extremely short text (1–2 words) may produce unreliable or undefined grade-level scores
- Non-English text may yield inaccurate readability scores as the formulas are designed for English
- Very large text payloads may time out or be rejected if they exceed request size limits
- Network or service unavailability returns a 5xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| text | string |
Output
Schema · Response
{
"type": "json",
"example": {
"words": 17,
"flesch_reading_ease": 90
}
}Tags
x402
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