# ONE Engine Array Frequency (T9)

> ONE Engine Array Frequency (T9) is a paid API for AI agents from one-search.one-engine.workers.dev, paid per call via x402, $0.018/call, status unknown (last checked 2026-10-02).

Computes frequency distribution of elements in a JSON array, with optional comparison against a second array.

## Facts

- Endpoint: POST https://one-search.one-engine.workers.dev/v3/array/frequency/t9?utm_source=zero.xyz
- Price: $0.018/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/one-engine-array-frequency-t9-a9233e19
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IqPMBp7Lsvqeu2nI_r3XD

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 one-engine-array-frequency-t9-a9233e19 -d '<json body>'
```

Example prompt: Can you count how many times each value appears in this list: ["apple","banana","apple","cherry","banana","apple"] and also compare it against this reference list ["apple","banana","date"]?

## When to prefer this

Choose this endpoint when you need to count element occurrences or compute a frequency distribution over a JSON array of up to 1000 items, especially when you also want to compare frequencies between two arrays. It is pay-per-call with no subscription needed, making it ideal for lightweight, on-demand statistical analysis in agent workflows.

## Known failure modes

- Array exceeds 1000 items — request rejected
- Invalid JSON array format for values field — validation error
- Missing required 'values' field — 400 error
- Payment not included or insufficient — 402 Payment Required
- Malformed comparison array in 'other' field — processing error

## How this service works

Low-cost pay-per-call utility APIs for autonomous agents using x402 on Base.

## Output

Returns an object containing frequency counts for each unique element in the input array, and optionally a comparison breakdown when a second array is provided. The response includes occurrence tallies per element, enabling ranking or distribution analysis.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "values"
 ],
 "properties": {
  "size": {
   "type": "integer"
  },
  "other": {
   "type": "array",
   "description": "Optional comparison array"
  },
  "offset": {
   "type": "integer"
  },
  "values": {
   "type": "array",
   "description": "JSON array with at most 1000 items"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/one-engine-array-frequency-t9-a9233e19/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from one-search.one-engine.workers.dev](https://www.zero.xyz/host/one-search.one-engine.workers.dev/llms.txt)