# Clink Forge State GDP Series

> Clink Forge State GDP Series is a paid API for AI agents from api.clinkforge.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Retrieves a time-series of U.S. state-level GDP data from government sources, with cryptographic provenance and attestation, paid per-call via x402/USDC.

## Facts

- Endpoint: GET https://api.clinkforge.com/v1/p/state-gdp-series
- 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/clink-forge-state-gdp-series-4e983b85
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VegDCLWmI-gqy-36MTTi6

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 clink-forge-state-gdp-series-4e983b85
```

Example prompt: Pull the state GDP time series for California from 2015 to 2023 — I need the data with full cryptographic provenance so I can verify it came from a government source.

## When to prefer this

Choose this endpoint when you need U.S. state-level GDP time series data with cryptographic provenance and attestation — especially when downstream consumers need to verify data authenticity without trusting a centralized API key-gated provider. Ideal for autonomous agents that can pay per-call in USDC without account setup, and for pipelines that require auditable, signed government-sourced economic data. Prefer alternatives if you need real-time GDP estimates, non-U.S. GDP data, or GDP at the county/metro level.

## Known failure modes

- Payment not settled — x402 payment flow fails or USDC balance insufficient, resulting in 402 response with no data
- Invalid entity code — unrecognized state code returns empty data or error
- Date range out of bounds — start/end dates outside available data window return empty rows
- Network timeout — upstream government data source temporarily unavailable
- Malformed query parameters — non-ISO date strings or oversized entity codes rejected at schema validation

## How this service works

Pay per call over x402. USDC on Base, no account, no API key. 28 government-sourced data products at $0.001–$0.05 per call, every response signed and provenance-chained.

## Output

Returns an array of GDP data rows for the specified state and date range, along with a provenance chain (source URL, observing authority, hash, and timestamp), a cryptographic attestation (signature, result digest, signing key ID), and a payment receipt confirming the $0.02 USDC per-call transaction. Each record includes a unique record ID.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "const": "GET"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "end": {
       "type": "string",
       "maxLength": 10
      },
      "start": {
       "type": "string",
       "maxLength": 10
      },
      "entity": {
       "type": "string",
       "maxLength": 8
      }
     },
     "additionalProperties": false
    }
   }
  },
  "output": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": [
   {
    "field": "value",
    "_record_id": "R-100"
   }
  ],
  "product": "example-product",
  "row_count": 1,
  "provenance": [
   {
    "hash": "sha256...",
    "authority": "AGENCY",
    "source_url": "https://agency.gov/data",
    "observed_at": "2026-08-25T00:00:00Z"
   }
  ],
  "attestation": {
   "signature": "base64...",
   "result_digest": "sha256...",
   "signing_key_id": "forge-signing-1"
  },
  "payment_receipt": {
   "amount_usd": 0.01,
   "settlement_ref": "0xtx..."
  },
  "product_version": 1
 },
 "description": "data rows + provenance chain + attestation"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/clink-forge-state-gdp-series-4e983b85/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.clinkforge.com](https://www.zero.xyz/host/api.clinkforge.com/llms.txt)