# x402engine Gemini 3 Flash LLM API

> x402engine Gemini 3 Flash LLM API is a paid API for AI agents from x402engine.app, paid per call via x402, $0.00829/call, status unknown (last checked 2026-10-12).

Runs Google's Gemini 3 Flash model via an OpenAI-compatible chat completions interface, pay-per-call with USDC micropayments

## Facts

- Endpoint: POST https://x402engine.app/api/llm/gemini-3-flash?utm_source=zero.xyz
- Price: $0.00829/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-gemini-3-flash-llm-api-45e9af2a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0Yp0AXnPGv1WtASKT5saX

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-gemini-3-flash-llm-api-45e9af2a -d '<json body>'
```

Example prompt: Ask Gemini 3 Flash to analyze this product description and suggest three improvements: 'Our widget is fast and durable, perfect for everyday use.' — pay per call with USDC so no subscription needed.

## When to prefer this

Choose this endpoint when you need fast, cost-effective LLM inference from Google's Gemini 3 Flash model without a monthly subscription, paying only per call in USDC. Ideal for AI agents with variable or bursty workloads, multimodal inputs (images, files, video URLs), or tool-calling pipelines. Prefer over direct Google API when you want HTTP 402 micropayment billing on Base, MegaETH, or Solana.

## Known failure modes

- Payment not settled — request rejected before inference begins
- Insufficient USDC balance — 402 response with payment requirements
- Malformed messages array — 400 validation error
- Unsupported content type or role — schema validation failure
- Model unavailable or overloaded — 503 or timeout
- Streaming not supported for all configurations — falls back or errors

## 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

An OpenAI-compatible JSON response containing the model name ('google/gemini-3-flash-preview'), an array of choices each with an assistant message (role, content), finish_reason, and a top-level 'content' field with the response text. When streaming is enabled, returns OpenAI-compatible SSE chunks.

## 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": {
      "seed": {
       "type": "integer",
       "description": "Model-supported seed; see /docs/llm-capabilities.md."
      },
      "stop": {
       "oneOf": [
        {
         "type": "string"
        },
        {
         "type": "array",
         "items": {
          "type": "string"
         },
         "maxItems": 4
        }
       ],
       "description": "Model-supported stop; see /docs/llm-capabilities.md."
      },
      "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."
      },
      "plugins": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "pdf"
        ],
        "properties": {
         "id": {
          "enum": [
           "file-parser"
          ],
          "type": "string"
         },
         "pdf": {
          "type": "object",
          "properties": {
           "engine": {
            "enum": [
             "native"
            ],
            "type": "string"
           }
          }
         }
        }
       },
       "description": "Optional native PDF parser only; automatically enabled for file inputs."
      },
      "messages": {
       "type": "arra
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "model": "google/gemini-3-flash-preview",
  "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-gemini-3-flash-llm-api-45e9af2a/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)