Request conventions

Standard request headers

Header	Required	Description
`X-API-Key`	Yes	API key; may appear only once
`Accept`	No	`application/json` is recommended
`Content-Type`	Yes for POST/PATCH	Use `application/json`
`X-LANG`	No	Language for error messages and translatable data
`X-TRACE-ID`	No	Caller-provided trace ID; the response returns the final value used

Language

X-LANG supports the following values:

en_US
es_ES
pt_BR
ru_RU
vi_VN
zh_CN

If the header is omitted or contains an unsupported value, en_US is used.

The msg in a successful response is always success and does not change with X-LANG. The msg in a failed response and translatable data fields such as region names use the requested language. The default language may be used when a translation is unavailable.

Trace IDs

The caller may send X-TRACE-ID. Its length cannot exceed 128 characters and it cannot contain line breaks. The response header returns the final trace ID. A new ID is generated when the caller omits the header or supplies an invalid value.

Parameter rules

JSON fields and query parameters use snake_case.
Each query parameter may appear only once.
Query parameters and JSON fields not listed in the relevant API article are rejected.
JSON strings, integers, and booleans must use the correct JSON types. Numbers are not automatically converted to strings, and strings are not converted to integers or booleans.
Enumeration values are case-sensitive and must use the uppercase values listed in this documentation.
Pass path identifiers as strings.
order_no is an opaque string. Store and pass it unchanged; do not depend on its prefix, length, or generation rules.

Rate limits

The Open API does not currently enforce a request rate limit.

Caching

All responses include:

Cache-Control: private, no-store

Do not cache responses containing balances, accounts, orders, resources, or connection credentials.