The Bullion API holds more than metal prices, but you couldn't see that in one place. The docs list endpoints. They don't show the range of data behind them.
So I built a data page. It lists everything the API has, in five groups.
Metal prices
Gold, silver, platinum, palladium and copper, each priced per troy ounce in 151 currencies. The prices are cached and refreshed hourly, so they are not live. The page says so.
Countries and economies
I added this group because central banks, interest rates and inflation are what move the price of gold and silver. A price on its own doesn't tell you why it moved.
- Central-bank gold: reported holdings for 52 countries, with monthly changes back to October 2016.
- Central-bank reserves: annual reserves for 176 countries and regions, with and without gold.
- Government finances: debt, debt to GDP, borrowing and interest payments.
- Policy rates, inflation and bond yields: for the US, the UK and the euro area.
- Money supply and central-bank balance sheets: for the countries where the definitions are published.
Calculated gold metrics
Moving averages, volatility, drawdown, carat prices per gram and the gold-silver ratio. These are worked out from the cached prices. Since I first wrote this, I have added period highs and lows, monthly returns with their coverage shown, and the correlation between gold and US real yields.
Holdings are not purchases
The decision I care about most is on the central-bank pages. A change in reported holdings looks like a country buying or selling gold. It often isn't. The number can move because of revaluations, revisions or reclassification.
I kept holdings separate from purchases and said so on the pages. The same goes for reserves: a change in value does not measure gold bought or sold. I would rather the page be plain about this than let someone read a purchase into a bookkeeping change.
Government debt has a similar problem. Scopes, periods and definitions differ between the US, the UK, the euro area and the EU member states, so the page says the figures can't be compared across geographies. I haven't solved that. Some measures are also not offered for some countries, because no official source backs them.
What is missing
The graphs and the country comparison I wanted are on the pages now. There is a price chart builder and each country has its own holdings history, and you can put up to six countries side by side.
What is still missing is the comparison across everything else. There is no way to chart a central bank's holdings against its bond yields, or to see the same country in the metals and the macro sections at once.