# Chit402 Chat Completions

> Chit402 Chat Completions 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).

Runs OpenAI-compatible chat completions paid per-call with real USDC on Base or Solana via the x402 payment protocol, returning a signed receipt.

## Facts

- Endpoint: POST https://api.chit402.com/v1/chat/completions
- 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-chat-completions-0564ca4d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_q0vc-fMDLsWGzCDz1QX6F

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-chat-completions-0564ca4d -d '<json body>'
```

Example prompt: Using Chit402, ask the xfuel/auto model with temperature 0.7 and up to 512 tokens: 'Explain the x402 payment protocol in three sentences' — I'm okay with the USDC mainnet charge and want back the signed receipt URL.

## When to prefer this

Choose Chit402 when you need pay-per-call LLM inference charged in real USDC on Base or Solana via the x402 protocol, with a signed on-chain receipt for every call. It is ideal for autonomous agents that must audit or account for AI spend cryptographically, or for applications that want metered inference without a subscription. Prefer it over standard OpenAI-compatible hosts when the x402 payment flow, cost-plus pricing transparency, or receipt verifiability is a requirement.

## Known failure modes

- Payment rejected or insufficient USDC balance — 402 Payment Required
- Invalid or unsupported model ID — 400 Bad Request
- Malformed messages array (missing role or content) — 422 Unprocessable Entity
- Rate limit or quota exceeded — 429 Too Many Requests
- Model unavailable or inference timeout — 503 Service Unavailable

## How this service works

Treasury desk and possession book for agent spend. Who paid which call — export, policy, evidence. POST /v1/chat/completions is the x402 USDC door on Base and Solana. Returns signed receipt + public verify_url. Paying this host is real mainnet USDC.

## Output

Returns an OpenAI-compatible chat completion object alongside a signed payment receipt and a public verify_url that can be used to confirm the on-chain USDC transaction on Base or Solana mainnet.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "type": "string",
   "description": "Model id from GET /v1/models; xfuel/auto routes automatically"
  },
  "stream": {
   "type": "boolean"
  },
  "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"
  },
  "max_tokens": {
   "type": "integer",
   "description": "Output token budget"
  },
  "temperature": {
   "type": "number",
   "maximum": 2,
   "minimum": 0
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "chatcmpl-abc123",
  "model": "xfuel/auto",
  "usage": {
   "total_tokens": 15,
   "prompt_tokens": 10,
   "completion_tokens": 5
  },
  "xfuel": {
   "verify_url": "https://api.xfuel.app/receipt/xfuel-abc123"
  },
  "object": "chat.completion",
  "choices": [
   {
    "index": 0,
    "message": {
     "role": "assistant",
     "content": "Hello!"
    },
    "finish_reason": "stop"
   }
  ],
  "created": 1700000000
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chit402-chat-completions-0564ca4d/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)