API Reference

Relai provides an OpenAI-compatible API. If you're familiar with the OpenAI API, you already know how to use Relai.

Base URLs

Region	Base URL
EU	https://eu.api.llmrelai.com/v1
US	https://us.api.llmrelai.com/v1

Authentication

All API requests require an API key in the Authorization header:

Authorization: Bearer rk-eu-your-api-key

Endpoints

POST /v1/chat/completions

Create a chat completion.

Request Body:

{
  "model": "smart",
  "messages": [
    {"role": "system", "content": "You are a helpful assistant."},
    {"role": "user", "content": "Hello!"}
  ],
  "temperature": 0.7,
  "max_tokens": 1000,
  "stream": false
}

Parameters:

Parameter	Type	Required	Description
model	string	Yes	Model ID or alias (smart, fast, cheap)
messages	array	Yes	Array of message objects
temperature	number	No	Sampling temperature (0-2, default: 1)
max_tokens	integer	No	Maximum tokens to generate
stream	boolean	No	Enable streaming (default: false)
tools	array	No	Function calling tools

Response:

{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1715000000,
  "model": "claude-sonnet-4.6",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello! How can I help you today?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 10,
    "completion_tokens": 8,
    "total_tokens": 18
  }
}

GET /v1/models

List available models.

Response:

{
  "object": "list",
  "data": [
    {
      "id": "claude-opus-4.7",
      "object": "model",
      "owned_by": "anthropic"
    },
    {
      "id": "gpt-5.5",
      "object": "model",
      "owned_by": "openai"
    }
  ]
}

GET /v1/balance

Get current credit balance.

Response:

{
  "credits_micro": 4500000,
  "credits_dollars": 4.50
}

GET /v1/keys

List API keys.

Response:

{
  "keys": [
    {
      "id": "key_abc123",
      "name": "Production",
      "prefix": "rk-eu-abc",
      "region": "eu",
      "rpm_limit": 60,
      "created_at": "2026-05-01T10:00:00Z",
      "last_used_at": "2026-05-08T12:30:00Z"
    }
  ]
}

POST /v1/keys

Create a new API key.

Request Body:

{
  "name": "Production Key",
  "rpm_limit": 60
}

DELETE /v1/keys/{id}

Revoke an API key.

Streaming

Enable streaming by setting stream: true. Responses use Server-Sent Events:

data: {"id":"chatcmpl-abc","choices":[{"delta":{"content":"Hello"}}]}

data: {"id":"chatcmpl-abc","choices":[{"delta":{"content":" there"}}]}

data: {"id":"chatcmpl-abc","choices":[{"delta":{},"finish_reason":"stop"}]}

data: [DONE]

Rate Limits

Rate limits are per API key:

Default: 60 requests per minute
Configurable up to 1000 RPM per key
Organization-wide limits available on request

SDKs

Use any OpenAI-compatible SDK by setting the base URL:

TypeScript:

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.RELAI_API_KEY,
  baseURL: "https://eu.api.llmrelai.com/v1",
});

Python:

from openai import OpenAI

client = OpenAI(
    api_key=os.environ["RELAI_API_KEY"],
    base_url="https://eu.api.llmrelai.com/v1",
)