Supposedly the Yahoo Finance API used to be the holy grail of finance data, providing reliable and accurate finance data for free. I’ve been working on a recent project which required ASX market data - specifically daily historical data (volume, open, close etc).
IEX Cloud has a great API and allows for a fairly high volume of calls. Unfortunately ASX market support has not yet been delivered, however appears to be in the pipeline with an unconfirmed delivery date.
I was about to purchase historical CSV market data however came across Alphavantage and the expanded
Alphavantage has ASX (as well as a number of other international exchanges) data available in a great API. Plus there are easy wrappers for your favourite language including Ruby. I would highly recommend using this free service if you require any historical ASX market data.