What are the authoritative sources for historic Bitcoin prices?
Ideally this will be an API for all major exchanges.
All historical data from any exchange available at Bitcoin Charts: Markets API
Historic Trade Data
Trade data is available as CSV, delayed by approx. 15 minutes. It will return the 2000 most recent trades. Format:
Returns CSV with columns:
Latest Kraken EUR trades: https://api.bitcoincharts.com/v1/trades.csv?symbol=krakenEUR
At the bottom of that linked google docs spreadsheet are instructions to download data from Mt Gox and many other Exchanges. Namely:
Go to this link: http://bitcoincharts.com/charts/mtgoxUSD#tgSzm1g10zm2g25zv
Click load raw data
This raw data only maintains daily prices. This is probably the closing price for the day, but I can't be sure of that.
I'm not sure how bitcoin charts actually collects this information from the other providers. I hope other
If you're looking for a one-stop shop for lots of different exchanges/markets, Coinigy provides historical crypto data. It's not free but probably one of the better sources.