Errors & rate limits | Classic Chess API

Application API errors use an HTTP status code and a JSON body with a machine-readable code and a human-readable message:

{
  "error": {
    "code": "missing_query",
    "message": "q is required."
  }
}

Status	Code	Meaning
400	`missing_query`	A required `q` parameter was empty.
400	`missing_player`	A required `player` parameter was empty.
400	`missing_opponent`	`head_to_head` mode needs an `opponent`.
400	`invalid_mode`	`mode` was not `summary` or `head_to_head`.
400	`invalid_pagination`	`page` or `page_size` was not a positive integer.
404	`not_found`	The requested public game or player archive is unavailable.
400	`invalid_query`	A filter is invalid, too long, or uses an unsupported output format.
429	`rate_limited`	Request budget exhausted. Back off; honor Retry-After when present. Proxy responses may be plain text or HTML.
503	`stats_unavailable`	The master database is temporarily not connected.