Responses

Method and path

POST/v1/responses

Base URL https://api.relayvia.dev/v1. Send the key as Authorization: Bearer sk-....

Common parameters

Requests are forwarded in the original format, so the original API's parameters work unless the next section says otherwise. This table lists the common ones; see the official reference for the rest.

Differences from the original API

• There is no server-side conversation state. previous_response_id, conversation, input items referenced by id (item_reference, or an item with an id and no type), reasoning items without encrypted_content and a stored prompt template return 400 unsupported_parameter. Send the whole conversation in input each turn. store is always false, and GET /v1/responses/<id> is not provided.
• tools[] accepts function and custom tools, and tool_search with execution: client, which Codex CLI runs locally. Other hosted tools return 400 unsupported_parameter.
• Web search is not available. web_search tools are removed before forwarding and the request runs normally without search, so Codex CLI keeps working. If web search is the only tool, or tool_choice names it, the request returns 400 instead.
• Remote files (input_file.file_url) return 400 unsupported_parameter; send the file inline as file_data.
• user, safety_identifier and prompt_cache_key are scoped to your account before forwarding, so prompt caches and user ids are never shared with other accounts.
• Events are forwarded as they arrive, and response.completed carries the usage. A : keepalive comment is sent after every 15 seconds without data. The model name in the response is the one you sent.
• A non-streaming request with no response within 95 seconds returns 500 upstream_timeout; use streaming for long outputs. Or send the header X-Robi-Keepalive: 1: if there is no response within 30 seconds you get a 200 right away and a space every 15 seconds until the JSON arrives, and a later failure arrives as an error object in the body.

Request examples

curl https://api.relayvia.dev/v1/responses \
  -H "Authorization: Bearer sk-..." \
  -H "Content-Type: application/json" \
  -d '{"model":"gpt-5.5","input":"Hello!"}'

from openai import OpenAI

client = OpenAI(base_url="https://api.relayvia.dev/v1", api_key="sk-...")
resp = client.responses.create(model="gpt-5.5", input="Hello!")
print(resp.output_text)

import OpenAI from "openai";

const client = new OpenAI({ baseURL: "https://api.relayvia.dev/v1", apiKey: "sk-..." });
const resp = await client.responses.create({ model: "gpt-5.5", input: "Hello!" });
console.log(resp.output_text);

Response and streaming examples

{
  "id": "resp_abc123",
  "object": "response",
  "status": "completed",
  "model": "gpt-5.5",
  "output": [
    {
      "type": "message",
      "role": "assistant",
      "content": [
        {
          "type": "output_text",
          "text": "Hello! How can I help?"
        }
      ]
    }
  ],
  "usage": {
    "input_tokens": 9,
    "output_tokens": 8,
    "total_tokens": 17
  }
}

event: response.created
data: {"type":"response.created","response":{"id":"resp_abc123","status":"in_progress","model":"gpt-5.5"}}

event: response.output_text.delta
data: {"type":"response.output_text.delta","delta":"Hello!"}

event: response.completed
data: {"type":"response.completed","response":{"id":"resp_abc123","status":"completed","model":"gpt-5.5","usage":{"input_tokens":9,"output_tokens":8,"total_tokens":17}}}

Errors this endpoint returns

Every code, its fixed message and what to do are on the error codes page.