# CheapestInference Chat Completions

> CheapestInference Chat Completions is a paid API for AI agents from api.cheapestinference.com, paid per call via x402, $20/call, status unknown (last checked 2026-09-13).

Run chat completions against 200+ open-source AI models via an OpenAI-compatible API at a flat per-call rate

## Facts

- Endpoint: POST https://api.cheapestinference.com/v1/chat/completions
- Price: $20/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cheapestinference-chat-completions-c7cd52fd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_u9WoewaOZ4ptPA3knFgfa

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 cheapestinference-chat-completions-c7cd52fd -d '<json body>'
```

Example prompt: Use CheapestInference to run this conversation through mistralai/Mistral-7B-Instruct: system prompt 'You are a helpful assistant', user message 'Summarize the key differences between REST and GraphQL in three bullet points' — flat rate, no token charges.

## When to prefer this

Choose this endpoint when you need OpenAI-compatible chat completions from open-source models (Llama, Mistral, etc.) at a predictable flat per-call cost rather than variable per-token pricing, especially when paying with USDC on Base via x402 protocol.

## Known failure modes

- Payment not received or invalid USDC transaction — 402 Payment Required
- Invalid or unsupported model identifier — 400 Bad Request
- Malformed messages array or missing required fields — 422 Unprocessable Entity
- Model temporarily unavailable — 503 Service Unavailable
- Rate limit exceeded — 429 Too Many Requests

## How this service works

Access 200+ open-source AI models through a single OpenAI-compatible API. Flat-rate pricing with no per-token charges. Pay with card or USDC on Base.

## Output

Returns an OpenAI-compatible JSON object with a 'choices' array containing the generated message content, finish reason, and model metadata for the selected open-source model.

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "choices": {
   "type": "array"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cheapestinference-chat-completions-c7cd52fd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.cheapestinference.com](https://www.zero.xyz/host/api.cheapestinference.com/llms.txt)