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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.  

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1. Authentication

All requests require an API key passed as a request header.
HeaderTypeRequiredValue
x-nxopen-api-keystringYesYour MSU Open API key
  • Example: x-nxopen-api-key: gw_xxxxxxxxxxxxxxxxxx
For instructions on how to obtain an API key, refer to the Getting Started with MSU Builder guide.
Keep the API key secure. Do not expose it in public repositories or client-side code.
 　

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2. Rate Limits

Rate limits are applied per API key. Higher limits are available upon request.
LevelRate Limit (RPS)Quota (RPD)
Default1 RPS1,000 RPD
Level 15 RPS50,000 RPD
Level 220 RPS100,000 RPD
To request a limit increase, contact the MSU Builder Team at contact_builder@nexpace.io.
RPS = Requests Per Second, RPD = Requests Per Day. Quota resets daily at 00:00 UTC.
 　

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3. Response Format

All responses use a common structure:
  • Success:
{

  "success": true,

  "data": { ... },

  "trace_id": "string"

}
  • Error (4xx / 5xx):
{

  "success": false,

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

  "trace_id": "string"

}