List all available BOJ statistical databases. Use this first to find the correct DB code before querying data. No API call needed — uses a static list of 40+ databases.

Get metadata (series codes, names, units, frequencies, layer structure) for a BOJ database. Use this to discover available series codes and understand the database structure before fetching actual data. NOTE: Large databases like CO (Tankan, 168k series) require a small limit (e.g. 20-50) to avoid overwhelming responses — use layer-based queries to navigate them.

Fetch time series data by SERIES_CODE(s). All specified codes must share the same frequency. Returns up to 250 series / 60,000 data points per request. If a code is invalid, the server tries metadata-assisted correction for close matches and returns concrete suggestions.

Fetch time series data by layer (hierarchical structure). Useful for browsing data by category within a database. Supports wildcard '*'. Returns up to 1,250 series / 60,000 data points per request.