# OpenAI-Compatible Chat Completions (x402, USDC, No Account Required)

> OpenAI-Compatible Chat Completions (x402, USDC, No Account Required) is a paid API for AI agents from agent-production-1daa.up.railway.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Runs OpenAI-compatible LLM chat completions (summarize, classify, extract, translate, generate, chat) paid per request in USDC on Base — no API key or account needed.

## Facts

- Endpoint: POST https://agent-production-1daa.up.railway.app/v1/chat/completions
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/openai-compatible-chat-completions-x402-usdc-no-account-required-ff5039ab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IBXO6IDNAcj4HOHRT6tq1

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-compatible-chat-completions-x402-usdc-no-account-required-ff5039ab -d '<json body>'
```

Example prompt: Using gpt-4o-mini, summarize the following article in 3 bullet points and keep the output under 300 tokens: 'Researchers at MIT have developed a new battery technology that can charge in under 5 minutes and last 10 years...'

## When to prefer this

Choose this endpoint when an AI agent needs LLM inference without setting up an OpenAI account or API key, and can pay per-call in USDC on Base via the x402 protocol. Ideal for crypto-native agent pipelines, cost-controlled loops (temperature=0 caching cuts costs automatically), or serverless agent workflows that need on-demand text generation, summarization, classification, or extraction without credential management.

## Known failure modes

- Insufficient USDC payment on Base results in 402 Payment Required
- Unsupported model name returns validation error
- max_tokens exceeds authorized payment ceiling — request rejected
- Malformed messages array returns 400 Bad Request
- Network or upstream OpenAI outage causes 502/503 error

## How this service works

LLM inference API for AI agents: OpenAI-compatible chat completions paid per request in USDC on Base. No account or API key. Summarize, classify, extract, translate, generate and chat with gpt-5.4-nano, gpt-5.4-mini, gpt-5.4, gpt-5.5, gpt-4o-mini and more. Misses billed at cost + 4% on actual token usage (upto scheme); deterministic repeats (temperature 0) are cache hits billed at 55% of provider price — loops get cheaper automatically. From $0.001/call, standard OpenAI POST format.

## Output

An OpenAI-format chat completion response object containing the model's generated text, finish reason, token usage counts, and model identifier. For deterministic (temperature=0) repeated calls, responses are served from cache at 55% of provider price.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "model": {
   "enum": [
    "gpt-5.4-nano",
    "gpt-5.4-mini",
    "gpt-5.4",
    "gpt-5.5",
    "gpt-4o-mini",
    "gpt-4o",
    "gpt-4.1-mini",
    "gpt-4.1"
   ],
   "type": "string",
   "description": "Upstream model to run"
  },
  "messages": {
   "type": "array",
   "description": "OpenAI chat messages array"
  },
  "max_tokens": {
   "type": "number",
   "description": "Output cap; the authorized payment ceiling scales with it"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/openai-compatible-chat-completions-x402-usdc-no-account-required-ff5039ab/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-production-1daa.up.railway.app](https://www.zero.xyz/host/agent-production-1daa.up.railway.app/llms.txt)