Know your data sources.

Commodities-API — latest, historical, time-series, fluctuation, and OHLC for 80+ commodities. METHODS: getLatestPrices, getHistoricalPrices, getTimeSeries, getFluctuation, convert, getOHLC, getOilPrices, getEnergyPrices

Nasdaq Data Link (formerly Quandl) — time-series datasets. Energy shortcuts for WTI, Henry Hub, OPEC, NG. GENERIC: getDataset, getDatasetMetadata, searchDatasets, listDatabases, getDatabase ENERGY SHORTCUTS: getWTIFutures, getNatGasFutures, getOPECBasketPrice, getHenryHubSpot CRITICAL USAGE RULES: 1. Dataset is addressed by databaseCode + datasetCode (e.g., 'CHRIS' + 'CME_CL1') 2. Time-series filters: startDate / endDate / limit / order / collapse / transform

OilPrice.com commodity price API. Key optional for demo endpoints; required for full history and all commodity codes. LATEST: getLatestPrices, getPrice, listCommodities, getOilPrices, getGasPrices, getNGLPrices HISTORY: getPastDay, getPastWeek, getPastMonth, getPastYear

USGS MRDS + USMIN — global mineral deposits + US mine-feature points (no auth). Upstream (MapServer WFS 2.0.0): - /services/wfs/mrds — ms:mrds (~304K worldwide deposits) - /services/wfs/usmin — ms:points + ms:polygons (US only) Rich per-record JSON: /mrds/json/{dep_id} returns 26+ subtables (commodities, materials, ages, ore body, production, references, rocks). Filters: commodity (CU/AU/AG/FE/LI/U/REE/PGE…), country (FIPS), US state, dev_stat (Past Producer/Producer/Occurrence/Prospect/Plant/Raw Prospect), bbox. §0 quirks: CQL_FILTER silently ignored by MapServer — handler emits OGC FILTER= XML (fes:Filter). fips_code stored with literal "f" prefix (fCI / f06065). code_list space-separated with leading space.