To my knowledge, the most popular index fund is Vanguard
They offer both Retail and Wholesale index funds. Most other providers only offer Wholesale funds, which means you either need minimum investment of $500K per fund, or have to buy through a financial advisor.
For example, Blackrock and BT both offer wholesale index funds.
Blackrock:
https://www.blackrock.com/au/individual/products/product-list#categoryId=122&lvl2=priceBT:
https://www.bt.com.au/investment/products/index-funds/Vanguard is the only one I know of that offers you Retail index funds. Minimum investment is $5K
But, the retail index funds are really expensive! Vanguard Retail Index Funds start at 0.90% fee p.a.
An alternative option is to buy ETFs that are basically ASX listed Index Funds. They are generally low fees, like 0.2% - 0.3%.
I'm in the process of running the numbers comparing Retail Indexed Funds vs ETFs. Let me know if you want to know more.