# OpenAI o3 Chat Completions (x402/USDC)

> OpenAI o3 Chat Completions (x402/USDC) is a paid API for AI agents from openai.mm.family, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Runs OpenAI o3 reasoning model chat completions, billed per call in USDC via x402 micropayment protocol with configurable reasoning effort and service tiers.

## Facts

- Endpoint: POST https://openai.mm.family/x402/v1/models/o3/chat/completions?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/openai-o3-chat-completions-x402-usdc-52e0c9ed
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ATOmf1-bQ_L3MPIShM4lr

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 openai-o3-chat-completions-x402-usdc-52e0c9ed -d '<json body>'
```

Example prompt: Use o3 with high reasoning effort to solve this problem: given a sorted array of integers, write an optimized algorithm in Python to find all pairs that sum to a target value — limit the response to 500 tokens and use the standard service tier.

## When to prefer this

Choose this endpoint when you need OpenAI's o3 reasoning model specifically — particularly for hard math, coding, logic, or multi-step reasoning tasks — and want to pay per call in USDC via the x402 protocol without a traditional API key subscription. Prefer o3:high or o3:xhigh for maximum reasoning depth, o3:low for speed, and flex tier for cost efficiency. Use over alternatives when you need the full o3 reasoning capability (vs o3-mini) or want crypto-native micropayment billing.

## Known failure modes

- Insufficient USDC balance — payment rejected before inference runs
- max_tokens set too high relative to available credit — quota exceeded
- Invalid model variant string — enum validation error
- Empty response if query is flagged as policy-violating (returned free of charge)
- Timeout on very large completions at flex tier due to deprioritized queue
- Malformed messages array (missing role or content) — 422 validation error

## How this service works

o3: OpenAI o3 chat completions, paid per call in USDC. Per 1M tokens in/out: Flex (default) 1.0/4.0, Standard 2.0/8.0, Fast 3.5/14.0; pick with service_tier. Plus $0.0005 (Base) or $0.0005 (Solana) per call; the quote charges input plus 10% of max_tokens. Levels: low, medium, high, xhigh (model o3:<level>). Empty answers are free. Rates: https://openai.mm.family/x402/pricing

## Output

Returns a JSON chat completion object containing the assistant's reply message, finish reason (e.g. 'stop'), prompt/completion/total token counts, the model used, and the service tier applied. The response mirrors the OpenAI chat completions API format.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "enum": [
    "o3",
    "o3:low",
    "o3:medium",
    "o3:high",
    "o3:xhigh"
   ],
   "type": "string"
  },
  "tools": {
   "type": "array"
  },
  "stream": {
   "type": "boolean"
  },
  "messages": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "role",
     "content"
    ],
    "properties": {
     "role": {
      "type": "string"
     },
     "content": {
      "type": "string"
     }
    }
   }
  },
  "max_tokens": {
   "type": "integer"
  },
  "service_tier": {
   "enum": [
    "flex",
    "default",
    "standard",
    "auto",
    "fast",
    "priority"
   ],
   "type": "string"
  },
  "response_format": {
   "type": "object"
  },
  "reasoning_effort": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": "chatcmpl-x",
  "model": "o3",
  "usage": {
   "total_tokens": 9,
   "prompt_tokens": 8,
   "completion_tokens": 1
  },
  "object": "chat.completion",
  "choices": [
   {
    "index": 0,
    "message": {
     "role": "assistant",
     "content": "Hello",
     "refusal": null
    },
    "finish_reason": "stop"
   }
  ],
  "service_tier": "flex"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/openai-o3-chat-completions-x402-usdc-52e0c9ed/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from openai.mm.family](https://www.zero.xyz/host/openai.mm.family/llms.txt)