# SignalHarness LLM Response JSON Extractor

> SignalHarness LLM Response JSON Extractor is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Extracts and returns structured JSON from a caller-supplied LLM response string, validating and parsing the embedded JSON payload.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/llm_response_json_extract/invoke
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-llm-response-json-extractor-8662763a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__vG9GbPm0bVr9RMgiiZxJ

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 signalharness-llm-response-json-extractor-8662763a -d '<json body>'
```

Example prompt: I just got a response back from an LLM that has JSON buried in it — can you extract just the JSON object from this string: '{"name": "Alice", "score": 42, "tags": ["vip", "active"]}'?

## When to prefer this

Choose this endpoint when you need a reliable, pay-per-call microservice to extract structured JSON from raw LLM output strings, especially in agentic pipelines where model responses may mix natural language with JSON and you need the JSON isolated and validated programmatically without standing up your own parsing infrastructure.

## Known failure modes

- Input string contains no valid JSON — returns error or empty result
- Malformed JSON in input that cannot be parsed — may return warnings
- Input exceeds 65536 character limit — request rejected
- Ambiguous or multiple JSON blocks in input — only one may be extracted
- Payment failure via x402 — request not processed

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a parsed JSON object under 'analysis_json', along with any warnings about the caller-supplied data, a service receipt with payment and execution metadata, and a status field indicating success or failure.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "request_json": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Verify the caller-supplied data before relying on this result."
   ],
   "service_id": "llm_response_json_extract",
   "analysis_json": "{\"example\":\"schema-valid caller-supplied data\"}",
   "evidence_scope": "caller_supplied_data"
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "llm_response_json_extract",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "5000",
   "resultSha256": "f9953c34d43ae0b16888cccb775f420eac797ad5a5e518633a9ac9cb76d2813c",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-llm-response-json-extractor-8662763a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)