FarOut LLM Gateway – Pay-Per-Call Chat Completions (GPT-5.5)

x402

FarOut LLM Gateway – Pay-Per-Call Chat Completions (GPT-5.5) is a paid API for AI agents from farouter.tech, paid per call via x402, $0.23/call, status unknown (last checked 2026-10-27).

Runs a chat completion request against GPT-5.5 (or any supported frontier model) with per-call USDC micropayment via x402 — no API key or account required.

Price / call$0.23

Seller volume →—

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StatusUnknown

How this service works

[OI]-compatible LLM inference API for autonomous agents. Supports reasoning, coding and chat workloads across 10 frontier models (GPT-5.5, GPT-5.6, GLM 5.3, Kimi K3, DeepSeek V4, MiniMax M3). Pay per request with USDC on Base using x402. No prepaid balance required, no API key, no account.

Output

Returns an OpenAI-compatible JSON object with a choices array containing the assistant's message and finish_reason, plus a usage object with prompt_tokens and completion_tokens counts.

Example use cases

On-demand coding assistant for an agent

“Have the FarOut gateway call DeepSeek V4 and ask it to write a Python function that validates an email address using regex — give it up to 500 tokens to respond, and pay per call so I don't need a subscription.”

Autonomous agent reasoning step

“My agent needs to decide which tool to use next — send this system prompt and the last 3 messages to Kimi K3 via FarOut and get back its reasoning, keeping it to 200 tokens max.”

Frontier model benchmarking without accounts

“Run the same math word problem through GPT-5.5 and GLM-5.3 on FarOut and compare their answers — pay per request in USDC so I don't have to set up separate API keys for each provider.”

Technical details

Endpoint

POSThttps://farouter.tech/v1/models/gpt-5.5/chat/completions?utm_source=zero.xyz

When to prefer

Choose this endpoint when you need on-demand LLM inference without pre-registering for an API key or maintaining a prepaid balance — ideal for autonomous agents that pay per action using x402 USDC micropayments on Base. It is especially useful when you want to route across multiple frontier models (GPT, Gemini, DeepSeek, GLM, Kimi, MiniMax) through a single OpenAI-compatible interface. Prefer it over direct provider APIs when your agent workflow demands trustless, accountless, per-call payment semantics.

Side effects

Payment rejected or insufficient USDC balance — HTTP 402 with payment requirements
Invalid model ID — returns 400 with an error indicating the model is not found
messages array empty or malformed — 400 validation error
max_tokens or max_completion_tokens too low for the requested task — response may be truncated with finish_reason=length
Network or upstream model provider outage — 502 or 503 error
Streaming SSE connection dropped mid-response if stream=true

Input

Schema · Request body

Field	Type	Description
model	string	Model id from GET /v1/models, e.g. glm-5.3. No provider prefix.
stream	boolean	SSE streaming.
messages	array	Chat messages, [OI]-compatible {role, content}.
max_tokens	integer	Output token budget. Sets your spending cap; actual usage is what gets settled (true-up).
temperature	number	Sampling temperature.
max_completion_tokens	integer	Alias of max_tokens (gpt-5.x models).

Output

Schema · Response

{
  "type": "json",
  "example": {
    "usage": {
      "prompt_tokens": 6,
      "completion_tokens": 8
    },
    "choices": [
      {
        "message": {
          "role": "assistant",
          "content": "Hello! How can I help?"
        },
        "finish_reason": "stop"
      }
    ]
  }
}

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