# SERP Stack Intent

Give a query, get Google + Bing + DuckDuckGo organic results in one response.

- endpoint: `GET https://marketplaceforaiagents.com/api/public/v1/serp-stack`
- category: intents
- price: $0.005 USDC per call (5000 atomic, 6 decimals)
- free tier: 3 calls per agent identity, shared across all endpoints (unknown/generic clients draw from a site-wide 100 successful free calls per UTC day; crawlers get none)
- settlement: USDC on Base mainnet `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`, payee `0x05e82e03753c7bc99fb24d10a876cce53f24b7b7`, scheme `exact`
- sandbox: append `?network=base-sepolia` for testnet USDC + mock data
- results key: `results`
- html: https://marketplaceforaiagents.com/listings/serp-stack

## What it returns

One query, three independent search indexes: Google, Bing and DuckDuckGo organic results in a single paid call. Use it when a single index is not enough evidence for a grounded answer.

## Use cases

- Cross-index grounding before answering
- Detect index disagreement on a claim
- Broad citation gathering in one call

## Parameters

| param | type | required | default | description |
| --- | --- | --- | --- | --- |
| `q` | string | yes | — | Search query sent to all three engines |
| `gl` | string | no | us | Country code for results |
| `hl` | string | no | en | Interface language code |
| `num` | integer | no | 10 | Results per engine |

## Example call

```bash
curl -s "https://marketplaceforaiagents.com/api/public/v1/serp-stack?q=example"
```

## Response shape

```json
{
  "intent": "serp-stack",
  "chain": [
    "google-search",
    "bing-search",
    "duckduckgo-search"
  ],
  "steps_run": 3,
  "results": {
    "google-search": {
      "note": "Normalized response of /api/public/v1/google-search"
    },
    "bing-search": {
      "note": "Normalized response of /api/public/v1/bing-search"
    },
    "duckduckgo-search": {
      "note": "Normalized response of /api/public/v1/duckduckgo-search"
    }
  }
}
```

## Payment

1. Call without `X-PAYMENT`. The first 3 calls per identity (across all endpoints) return 200 with an `X-Free-Calls-Remaining` header.
2. After that the response is `402` with an `accepts[]` requirement.
3. Sign the EIP-3009 USDC authorization, base64 the x402 payload, resend as `X-PAYMENT`.
4. Settlement receipt returns in the `X-PAYMENT-RESPONSE` header.