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Base URL

All API requests are made to: 
https://api.modelstack.cc

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OpenAI-Compatible Format

ModelStack follows the OpenAI API format, so you can use any existing OpenAI SDK or HTTP client. Just change the base URL and API key.

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Available Endpoints

MethodEndpointDescription
POST/v1/chat/completionsCreate a chat completion
GET/v1/modelsList available models

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Authentication

All requests require an API key passed via the Authorization header: 
Authorization: Bearer your_api_key
API keys are created and managed from your dashboard.

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Request Format

All requests use JSON. Set the Content-Type header: 
Content-Type: application/json

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Response Format

Responses follow the OpenAI response format: 
{
  "id": "chatcmpl-abc123",
  "object": "chat.completion",
  "created": 1699000000,
  "model": "claude-sonnet-4-5",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hello! How can I help you?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 10,
    "completion_tokens": 15,
    "total_tokens": 25
  }
}

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Streaming

ModelStack supports Server-Sent Events (SSE) streaming. Set "stream": true in your request body to receive incremental responses.

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Rate Limits

Rate limits depend on your subscription plan:
PlanRate Limit
Starter15 RPM
Pro40 RPM
Max60 RPM
When you exceed your rate limit, requests return a 429 Too Many Requests error.