# PennyRail AI Chat Mini (v1)

> PennyRail AI Chat Mini (v1) is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Provides access to a compact AI chat/language model via a paid x402 micropayment endpoint, returning a model-generated text response to a given input.

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/premium/ai.chat-mini--v1-chat
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-ai-chat-mini-v1-89a37bc1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_M2y8vm37aMJLjD-_rS2jJ

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-ai-chat-mini-v1-89a37bc1 -d '<json body>'
```

Example prompt: Send this message to the PennyRail mini chat model and get a response: 'Summarize the key differences between REST and GraphQL APIs in two sentences.'

## When to prefer this

Choose this endpoint when you need a lightweight, per-call AI chat completion with no subscription commitment, billed via x402 USDC micropayments at $0.02 per call. Ideal for agent pipelines that require cost-controlled, pay-as-you-go LLM access without managing API keys or monthly billing. Best suited for simple prompt-response tasks where a 'mini' model's capability is sufficient.

## Known failure modes

- Payment not included or insufficient (402 Payment Required — x402 payment header missing or underfunded)
- Malformed input object — missing required 'input' field returns a validation error
- Model unavailable or overloaded — upstream inference service may return 5xx errors
- Rate limiting if too many requests are sent in quick succession
- Ambiguous or empty input may yield low-quality or empty model output

## How this service works

Machine-readable settlement service

## Output

An object containing the AI model's generated text response to the provided input, returned as a loosely-typed JSON object with model-specific output fields.

## 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-ai-chat-mini-v1-89a37bc1/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)