> ## Documentation Index
> Fetch the complete documentation index at: https://docs.msu.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

The MSU Open API provides read access to MapleStory Universe data — including accounts, characters, items, game metadata, and marketplace listings. Builders can use it to create tools, dashboards, and Synergy Apps that connect with the MSU ecosystem.

* Base URL: [https://openapi.msu.io](https://openapi.msu.io)

 

## **1. Authentication**

All requests require an API key passed as a request header.

| **Header**       | **Type** | **Required** | **Value**             |
| :--------------- | :------- | :----------- | :-------------------- |
| x-nxopen-api-key | string   | Yes          | Your MSU Open API key |

* **Example**: x-nxopen-api-key: gw\_xxxxxxxxxxxxxxxxxx

<Info>
  For instructions on how to obtain an API key, refer to the Getting Started with MSU Builder guide.
</Info>

<Warning>
  Keep the API key secure. Do not expose it in public repositories or client-side code.
</Warning>

 　

## **2. Rate Limits**

Rate limits are applied per API key. Higher limits are available upon request.

| **Level** | **Rate Limit (RPS)** | **Quota (RPD)** |
| :-------- | :------------------- | :-------------- |
| Default   | 2 RPS                | 3,000 RPD       |
| Level 1   | 10 RPS               | 50,000 RPD      |
| Level 2   | 30 RPS               | 200,000 RPD     |

<Info>
  To request a limit increase, contact the MSU Builder Team at [contact\_builder@nexpace.io](mailto:contact_builder@nexpace.io).
</Info>

<Note>
  RPS = Requests Per Second, RPD = Requests Per Day. Quota resets daily at 00:00 UTC.
</Note>

 　

## **3. Response Format**

All responses use a common structure:

* **Success:**

```json theme={null}
{

  "success": true,

  "data": { ... },

  "trace_id": "string"

}
```

* **Error (4xx / 5xx):**

```json theme={null}
{

  "success": false,

  "error": { "code": 0, "message": "string" },

  "trace_id": "string"

}
```

　

***