# 24K Labs Readability Score API

> 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 text and returns word/sentence/syllable counts, reading time, and multiple readability grade-level scores (Flesch, Flesch-Kincaid, Gunning Fog, SMOG, ARI, Coleman-Liau) in a single call.

## Facts

- Endpoint: POST https://api.24klabs.ai/api/readability-score
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/24k-labs-readability-score-api-0e0f0df3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_R3KF1-cErb4S9iWxhy53M

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability 24k-labs-readability-score-api-0e0f0df3 -d '<json body>'
```

Example prompt: Can you check the readability of this article draft and give me the Flesch Reading Ease score, Gunning Fog index, and estimated reading time? Here's the text: [paste text]

## When to prefer this

Choose this endpoint when you need multiple standard readability metrics computed simultaneously in one call rather than calling separate services. Ideal for content pipelines, writing assistants, educational tools, compliance checks, or any workflow that needs to assess text complexity at scale with a predictable per-call cost of $0.002 USDC.

## Known failure modes

- Empty or missing text body returns an error
- Extremely short text (single word) may yield unreliable or undefined grade-level scores
- Very large text payloads may exceed request size limits
- Non-English text may produce inaccurate syllable counts and readability scores since formulas are calibrated for English

## 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 JSON object containing word count, sentence count, syllable count, estimated reading time, Flesch Reading Ease score, Flesch-Kincaid grade level, Gunning Fog index, SMOG index, ARI (Automated Readability Index), and Coleman-Liau index — all computed in a single API call from the submitted text.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "words": 17,
  "flesch_reading_ease": 90
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/24k-labs-readability-score-api-0e0f0df3/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.24klabs.ai](https://www.zero.xyz/host/api.24klabs.ai/llms.txt)