# x402engine Aion-3.0 LLM API

> x402engine Aion-3.0 LLM API is a paid API for AI agents from x402engine.app, paid per call via x402, $0.022008/call, status unknown (last checked 2026-10-12).

Run inference against the Aion-3.0 large language model via pay-per-call HTTP 402 micropayment, with tool-calling and streaming support

## Facts

- Endpoint: POST https://x402engine.app/api/llm/aion-3.0?utm_source=zero.xyz
- Price: $0.022008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-aion-3-0-llm-api-a06ca5a7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_eeMh9JIBJRNhGU6Om8J1j

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 x402engine-aion-3-0-llm-api-a06ca5a7 -d '<json body>'
```

Example prompt: Send these messages to Aion-3.0 and get back a response: system prompt 'You are a helpful assistant', user message 'Explain quantum entanglement in simple terms' — limit the output to 512 tokens and stream the result.

## When to prefer this

Choose this endpoint when you need access to the Aion-3.0 model specifically, want to pay per call in USDC/USDm without a subscription, are building a crypto-native or autonomous agent that uses HTTP 402 for payment, or need OpenAI-compatible chat completion with optional tool-calling and streaming at roughly $0.022 per call.

## Known failure modes

- Payment not settled — 402 response if USDC/USDm balance insufficient
- Invalid messages array (empty or missing required role field) — 422 validation error
- max_tokens exceeded model context limit — truncated or error response
- Unsupported tool schema triggers function-calling failure
- Stream interrupted mid-response if network drops after payment
- Model unavailable or overloaded — 503 or timeout

## How this service works

125 production APIs behind HTTP 402 micropayments. 87 LLMs, Kling V3 and Hailuo video generation, image generation, code execution, travel search, web scraping, TTS, and transaction simulation. Pay with USDC on Base, USDm on MegaETH, or USDC on Solana.

## Output

Returns an OpenAI-compatible JSON object containing the model name ('aion-labs/aion-3.0'), an array of choice objects each with a message (role + content), finish_reason, and index. If streaming is enabled, returns SSE chunks in OpenAI format. Tool calls are embedded in the assistant message when triggered.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "bodyType",
    "body",
    "method"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "messages"
     ],
     "properties": {
      "tools": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "function"
        ],
        "properties": {
         "type": {
          "enum": [
           "function"
          ],
          "type": "string"
         },
         "function": {
          "type": "object",
          "properties": {
           "name": {
            "type": "string"
           },
           "strict": {
            "type": "boolean"
           },
           "parameters": {
            "type": "object"
           },
           "description": {
            "type": "string"
           }
          }
         }
        }
       },
       "description": "Client-executed function definitions; return results using role=tool and tool_call_id."
      },
      "top_p": {
       "type": "number",
       "description": "Model-supported top_p; see /docs/llm-capabilities.md."
      },
      "stream": {
       "type": "boolean",
       "description": "Return live OpenAI-compatible SSE after payment settlement."
      },
      "messages": {
       "type": "array",
       "items": {
        "type": "object",
        "anyOf": [
         {
          "required": [
           "content"
          ]
         },
         {
          "required": [
           "tool_calls"
          ]
         }
        ],
        "required": [
         "role"
        ],
        "properties": {
         "name": {
          "type": "string"
         },
         "role": {
          "enum": [
           "system",
           "developer",
           "user",
           "assistant",
           "tool"
          ],
          "type": "string"
         },
         "content": {
          "oneOf": [
           {
            "type": "string"
           },
           {
            "type": "null"
           },
           {
            "type": "array",
            "items": {
             "type": "object",
             "required": [
              "type"
             ],
             "properties": {
              "type": {
               "enum": [
                "text"
               ],
               "type": "string"
              }
  
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "model": "aion-labs/aion-3.0",
  "choices": [
   {
    "index": 0,
    "message": {
     "role": "assistant",
     "content": "Hello!"
    },
    "finish_reason": "stop"
   }
  ],
  "content": "Hello!"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402engine-aion-3-0-llm-api-a06ca5a7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402engine.app](https://www.zero.xyz/host/x402engine.app/llms.txt)