# Chit402 Paid AI Inference via x402

> Chit402 Paid AI Inference via x402 is a paid API for AI agents from api.chit402.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Submits a paid AI inference request over the x402 USDC payment protocol, returning a receipted task ID and payment reference for treasury tracking.

## Facts

- Endpoint: POST https://api.chit402.com/v1/responses
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/chit402-paid-ai-inference-via-x402-f35fddc4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3zxVjy9iRe4_6pxf9gR-V

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 chit402-paid-ai-inference-via-x402-f35fddc4 -d '<json body>'
```

Example prompt: Use my Base wallet 0xAbc...123 to send a paid inference request to Chit402 for up to 500 tokens using the xfuel/auto model — ask it 'What is the capital of France?' and give me back the task ID and receipt URL so I can log the spend.

## When to prefer this

Choose this endpoint when you need verifiable, receipted AI inference paid per-call in USDC on Base via the x402 protocol — especially for autonomous agent fleets that require treasury reconciliation, spend export, or compliance evidence. Prefer it over generic OpenAI-compatible endpoints when on-chain payment proof, cost-plus pricing transparency, and per-call receipt URLs are required for auditing or policy enforcement.

## Known failure modes

- Insufficient USDC balance or payment failure — payment not settled, task rejected
- Invalid or unsupported model_id — returns error indicating model not found
- Malformed messages array (missing role or content) — validation error returned
- Unsupported chain_id or rail — only 'base' and 'usdc' are accepted
- max_tokens exceeds model limits — request rejected or truncated
- Invalid sender address format — request rejected with address parse error

## How this service works

Who paid which call — export, policy, evidence. Possession book for agent spend.

## Output

Returns a JSON object with status ('accepted'), a unique task_id, the gross and net USDC amounts (in 6-decimal base units), the fee deducted, the payment rail used, a payment_ref (on-chain transaction reference on Base), and a verify_url pointing to a hosted receipt on xfuel.app for treasury verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "amount": {
   "type": "string",
   "description": "Gross task value in USDC base units (6 decimals)"
  },
  "sender": {
   "type": "string",
   "description": "0x address that owns/pays for the task"
  },
  "payment": {
   "type": "object",
   "properties": {
    "rail": {
     "enum": [
      "usdc"
     ],
     "type": "string",
     "description": "Payment rail; use \"usdc\""
    }
   }
  },
  "chain_id": {
   "type": "string",
   "description": "Settlement chain; \"base\" for USDC settlement"
  },
  "messages": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "role",
     "content"
    ],
    "properties": {
     "role": {
      "enum": [
       "system",
       "user",
       "assistant"
      ],
      "type": "string"
     },
     "content": {
      "type": "string"
     }
    }
   },
   "description": "OpenAI-style chat messages array"
  },
  "model_id": {
   "type": "string",
   "description": "Model id from GET /v1/models; xfuel/auto routes automatically"
  },
  "input_hash": {
   "type": "string",
   "description": "keccak256 of your input (optional; for proof binding)"
  },
  "max_tokens": {
   "type": "integer",
   "description": "Output token budget (default 500)"
  },
  "message_type": {
   "enum": [
    "inference_request"
   ],
   "type": "string",
   "description": "Task type; only inference_request is supported via x402"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "status": "accepted",
  "task_id": "ai-task-12345",
  "fee_amount": "250",
  "net_amount": "49750",
  "verify_url": "https://api.xfuel.app/receipt/ai-task-12345",
  "payment_ref": "base:0x...",
  "gross_amount": "50000",
  "payment_rail": "usdc"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chit402-paid-ai-inference-via-x402-f35fddc4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.chit402.com](https://www.zero.xyz/host/api.chit402.com/llms.txt)