Point-in-time (vintage) economic data from FRED's ALFRED archive — what an economic figure was AS FIRST REPORTED / as known on a past date, before later revisions. Give a seriesId (e.g. GDP, GDPC1, PAYEMS, INDPRO) and an asOf date to get the observations exactly as they stood on that date; omit asOf to get the current (latest-revised) values. Also returns the series' vintage (revision) dates — every date the series was revised. Free, public-domain (FRED). Critical for honest backtesting and macro research: it eliminates look-ahead bias (e.g. GDP for 2020Q1 was first reported far lower than today's revised figure). No LLM and no real-time API gives this — it's the archived state of the data through time. Pair with econ.fred (current series) and econ.fred-releases (release calendar).