# PennyRail GPT-4o Mini Inference

> PennyRail GPT-4o Mini Inference is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Runs GPT-4o Mini LLM inference via a paid micropayment-gated API endpoint costing $0.01 USDC per call

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/standard/ai.llm-mini--gpt-4o-mini-inference
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-gpt-4o-mini-inference-5ef608ec
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Z-GFxc-MjwyDbmkX9KPFW

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 pennyrail-gpt-4o-mini-inference-5ef608ec -d '<json body>'
```

Example prompt: Use the PennyRail GPT-4o Mini endpoint to generate a short product description for a noise-cancelling bluetooth headphone — I'm okay with the $0.01 USDC charge per call.

## When to prefer this

Choose this endpoint when you need cheap, pay-per-call GPT-4o Mini inference without managing your own OpenAI API key, especially in agentic or automated workflows that support the x402 micropayment protocol and USDC billing. Ideal for low-volume, cost-sensitive inference tasks where $0.01 per call pricing is attractive and no monthly subscription commitment is desired.

## Known failure modes

- Payment failure or insufficient USDC balance causes 402 Payment Required
- Malformed input object missing required 'input' field causes 400 Bad Request
- Upstream OpenAI API unavailability causes 502 or 503 errors
- Rate limiting by the PennyRail platform may cause 429 Too Many Requests
- Malformed x402 payment header causes authentication/payment rejection

## How this service works

Machine-readable settlement service

## Output

A JSON object containing the LLM's generated response to the provided input, with schema varying based on the underlying model's output format; the response is open-ended (additionalProperties: true) and may include generated text, token counts, or other completion metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-gpt-4o-mini-inference-5ef608ec/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)