# ONE Engine Array Flatten

> ONE Engine Array Flatten 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).

Flattens a nested JSON array into a single-level array, with optional size and offset parameters.

## Facts

- Endpoint: POST https://one-search.one-engine.workers.dev/v3/array/flatten/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-flatten-2651dc85
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KIkx4zO3bf4RmKBI-pcgr

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-flatten-2651dc85 -d '<json body>'
```

Example prompt: Can you flatten this nested JSON array for me: [[1,2],[3,[4,5]],6] — I want it as a single flat list, limited to 10 items starting at offset 0.

## When to prefer this

Choose this endpoint when you need a simple, low-cost, pay-per-call utility to flatten nested JSON arrays without standing up your own transformation logic. Ideal for AI agents that occasionally need to normalize nested data structures from external APIs, especially when operating in a crypto-native x402 payment context on Base. Not suitable for very large arrays exceeding 1000 items.

## Known failure modes

- Input array exceeds 1000 items — request will be rejected
- Malformed JSON in the values field — will return a parse error
- Invalid offset or size values (negative integers or non-integer types) — validation error
- Payment failure via x402 on Base — 402 response before processing begins
- Empty values array — may return empty result or error depending on server handling

## How this service works

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

## Output

Returns a JSON object containing the flattened (single-level) version of the input array, along with any metadata from the operation. The flattened array has all nested sub-arrays unwound into a single sequential list, optionally trimmed by size and starting at offset.

## 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-flatten-2651dc85/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)