API rate limits and authentication

Authentication

Use query-parameter auth in public examples.

Request budgets

Plan limits

429 behavior

Use response headers to back off cleanly.

Anonymous USD requests that hit the no-key evaluation budget include X-RateLimit-* headers. On a 429, use Retry-After and X-RateLimit-Window to decide whether the minute, hour, day, endpoint, or concurrency budget was the binding constraint.

{
  "detail": "Anonymous USD API access is limited to 100 requests per day. Subscribe for an API key and higher limits: https://fxmacrodata.com/subscribe",
  "code": "anonymous_usd_rate_limit_exceeded"
}

Efficiency

Reduce quota use before adding retries.

• Send Accept-Encoding: gzip on requests. Most HTTP clients negotiate this automatically.
• Use If-None-Match with the latest ETag when polling the same resource.
• Pass ?limit= on history endpoints when you only need recent rows.
• Use /v1/latest/* and /v1/recent/* routes when you only need the newest records.
• Stay below the concurrency cap when polling multiple currencies or indicators in parallel.