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Explanation

Essentials

The foundations every integration needs, written once and linked from everywhere. Read these before you write much code — they're all short, and they'll save you grief. The UltraCart API is organized around REST and JSON: resource-oriented URLs, defined with the OpenAPI (Swagger) specification, with JSON for the request and response bodies wherever possible.

Getting started​

  • Authentication — OAuth 2.0 for multi-merchant apps, or a Simple Key for in-house automation.
  • OAuth 2.0 Guide — register a developer application and walk the full authorization-code flow to a Bearer access token.
  • Versioning — the X-UltraCart-Api-Version header, required on every request.
  • Download and install your SDK of choice, then review the samples to jump-start your project.

How requests and responses work​

  • Standard Responses — the success / error / metadata envelope shared by every endpoint.
  • Errors — HTTP status codes and the structured error object.
  • Object Identifiers — OIDs, their human-friendly companions, and how to set or clear them.
  • Expanding Objects — the _expand parameter for partial objects and leaner payloads.
  • Pagination — paging large result sets with _offset and result_set metadata.
  • Sorting — ordering results with the _sort parameter.
  • Date/Times — ISO-8601 everywhere.

Operating in production​

  • Rate Limiting — quotas, the leaky-bucket algorithm, and the no-concurrency rule.
  • Request IDs — the X-UltraCart-Request-Id header for tracing and support.
  • Webhooks — asynchronous event delivery instead of polling.

Once you know the essentials, head to the API Reference for the per-endpoint details.

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