# OpenAI o4-mini Chat Completions (x402)

> OpenAI o4-mini Chat Completions (x402) 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 o4-mini reasoning model chat completions with per-call USDC micropayment via x402 protocol, supporting adjustable reasoning effort and service tiers.

## Facts

- Endpoint: POST https://openai.mm.family/x402/v1/models/o4-mini/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-o4-mini-chat-completions-x402-f596b153
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_9VZbr5OgS5jNo1wc_hzsJ

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-o4-mini-chat-completions-x402-f596b153 -d '<json body>'
```

Example prompt: Use o4-mini with high reasoning effort to solve this multi-step math problem: if a train travels 120 miles in 90 minutes and then 200 miles in 2 hours, what is its average speed over the entire journey? Use the standard service tier and allow up to 1024 output tokens.

## When to prefer this

Choose this endpoint when you need OpenAI's o4-mini reasoning model with pay-per-call USDC micropayments (no subscription required), adjustable reasoning depth (low/medium/high/xhigh), and flexible cost-performance trade-offs via service tiers (flex is cheapest at $0.55/$2.2 per 1M tokens). Prefer over full o4 when cost efficiency matters and the task doesn't require maximum model capacity. Prefer over GPT-4o-class endpoints when structured multi-step reasoning is the priority.

## Known failure modes

- Insufficient USDC balance or x402 payment failure — returns 402 Payment Required
- Invalid model enum value — returns 400 Bad Request
- max_tokens exceeds model context limit — returns 400 or truncated response
- Rate limiting on the chosen service tier — returns 429 Too Many Requests
- Upstream OpenAI API error or timeout — returns 500 or 503

## How this service works

o4-mini: OpenAI o4 Mini chat completions, paid per call in USDC. Per 1M tokens in/out: Flex (default) 0.55/2.2, Standard 1.1/4.4, Fast 2.0/8.0; 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 o4-mini:<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'), token usage breakdown (prompt, completion, total tokens), the model and service tier used, and a unique completion ID. Empty responses (no content) are billed at zero.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "enum": [
    "o4-mini",
    "o4-mini:low",
    "o4-mini:medium",
    "o4-mini:high",
    "o4-mini: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": "o4-mini",
  "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-o4-mini-chat-completions-x402-f596b153/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)