Multi asset/Currency/portfolio backtest

Hey guys, I am intending to backtest a strategy into different markets and obtain its overall performance. Mt4 isn’t making it easier and I started looking online. But most of are priced and im not really sure about their accuracy either. Manual testing is a little time consuming and tedious also. Can you guys recommend a good “portfolio” backtester?

I have heard of R which is free but still I would like to hear you as many as possible. (haven’t started it yet)

Any guidance is appreciated, thanks!!