Focus stacking software

Was looking at DxO to use with my E-M1 mkiii since it has great noise reduction magic. What I didn't realise was that it doesn't do focus stacking (which I have never tried but would like to).

I'll sound like a d1ck, but I'm not signing up to Adobe's products, so looking for recommendations for good focus stacking software that isn't *too* hard for an old fart to learn.

Cheers.