I used Earmaster a few years ago. It is not free but it covers everything from sight singing, which works fairly decently, to rhythm detection/dictation, chord

I used Earmaster a few years ago. It is not free but it covers everything from sight singing, which works fairly decently, to rhythm detection/dictation, chord detection, melodic dictation, interval training, etc. It was a ton of practice and for me not very fun. I already knew quite a bit of theory but after putting in the work it's helped a lot. Prior to this I had only done some sight singing, basic interval training, and some basic chord progression detection. I can pretty much play close to instantly anything I hear in my head. I can also play anything I hear in real life as well, almost, if the music is incredibly fast or complex I might not remember it well enough to do so. Even if I can't play something I hear though in real life I can break down the higher level parts and structures pretty quickly at the very least. Either way, if you're new to this or don't want to pay for software since you can probably do a lot of this for free, I would definitely start out with sight singing. It'll speed up learning intervals and melodic dictation much faster than if you don't learn how to do it.