# SignalHarness HTTP Header Audit

> SignalHarness HTTP Header Audit is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Analyzes HTTP response headers from a URL for security, caching, and discovery best practices, returning categorized findings and pass/fail results.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/http_header_audit/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-http-header-audit-8ca35107
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Z8Dbwa3CqGmzihKViNkLL

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-http-header-audit-8ca35107 -d '<json body>'
```

Example prompt: Can you audit the HTTP headers for https://example.com — I got back a 200 status with these headers: [['content-type','text/html'],['cache-control','no-store'],['x-frame-options','DENY']] — tell me what security or caching headers are missing or misconfigured.

## When to prefer this

Choose this endpoint when you need a structured, machine-readable audit of HTTP response headers — especially for security posture checks (CSP, HSTS, X-Frame-Options), cache configuration validation, or pre-launch compliance reviews. It's ideal for AI agents that have already fetched HTTP headers from a target URL and need to classify and score them without writing custom header-checking logic. Prefer it over generic HTTP inspection tools when you need categorized findings (security/cache/discovery) and a clear pass/fail verdict at $0.01 per call.

## Known failure modes

- Invalid or non-HTTPS URL returns schema validation error
- Headers array malformed or exceeds 128 entries causes rejection
- Status code outside 100–599 range is rejected
- Unreachable or rate-limited upstream service may return an error status
- Missing required 'headers' field causes bad request

## 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

A structured JSON result with an overall pass/fail status, categorized findings broken into security, caching, and discovery summaries (each listing present and missing headers), a list of normalized headers, and a replay flag. Also includes a signed receipt with payment and execution metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "pattern": "^https://",
   "maxLength": 2048,
   "minLength": 9
  },
  "status": {
   "type": "integer",
   "maximum": 599,
   "minimum": 100
  },
  "headers": {
   "type": "array",
   "items": {
    "type": "array",
    "items": {
     "type": "string",
     "maxLength": 8192,
     "minLength": 0
    },
    "maxItems": 2,
    "minItems": 2
   },
   "maxItems": 128,
   "minItems": 1
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "result": "pass",
   "status": 0,
   "findings": [
    {
     "code": "duplicate_header",
     "header": "example",
     "severity": "info"
    }
   ],
   "sourceUrl": "example",
   "cacheSummary": {
    "missing": [
     "example"
    ],
    "present": [
     "example"
    ]
   },
   "securitySummary": {
    "missing": [
     "example"
    ],
    "present": [
     "example"
    ]
   },
   "discoverySummary": {
    "missing": [
     "example"
    ],
    "present": [
     "example"
    ]
   },
   "normalizedHeaders": [
    {
     "name": "example",
     "values": [
      "example"
     ]
    }
   ]
  },
  "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": "http_header_audit",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "2e6f0112ecd6a6aa620f18b3534e611c60f827bcd353b606f3640d5d1dbfc6f7",
   "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-http-header-audit-8ca35107/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)