Spotify: The best-known free streaming service that lets you listen to any song of your choice. The only thing you will have to deal with is to put up with ads if you don't want to pay
Pandora: Apart from free music streaming, it is the easiest way to find music similar to the songs you already like hearing. It recommends you songs according to your preferences
LiveOne: Like many other apps it does not force you to make any account for hearing music. Just another app where you can hear to music without paying any money
Tidal: It offers streams of the complete library of 80 million tracks that too for free. This streaming app is a blessing for people living in US
YouTube Music: YouTube started this service in the year 2015. Although you're limited to streaming the service's selection, but there's a considerable catalogue to choose from
Jango Radio: It is another free online music streaming service available worldwide. It has comparatively lesser ads as compared to other apps
SoundCloud: The free tier offers over 120 million tracks, mixes, podcasts and more, though quality is not the surety