Any series in the Federal Reserve's FRED database (800k+ US & international economic time series). HOW TO USE: if you know the series id, pass seriesId to get the series metadata (title, units, frequency, seasonal adjustment, observation range, last updated) + its most-recent observations (date + value, newest first; optionally bound the range with start/end YYYY-MM-DD and cap with limit). If you DON'T know the id, pass query to full-text search the catalog (returns ids + titles + units + frequency, most-popular first) — then call again with the seriesId you found. Popular ids: UNRATE (unemployment rate), CPIAUCSL (CPI), PCEPI (PCE price index), GDP / GDPC1 (nominal / real GDP), PAYEMS (nonfarm payrolls), FEDFUNDS (fed funds rate), DGS10 / DGS2 (10yr / 2yr Treasury), T10Y2Y (10y-2y spread), MORTGAGE30US (30yr mortgage), SP500, VIXCLS (VIX), DEXUSEU (USD/EUR), DCOILWTICO (WTI oil), HOUST (housing starts), UMCSENT (consumer sentiment), M2SL (M2 money supply). Each series' units and frequ