The best alternatives to Doppler 2.3 are SoundCloud iOS, VOX for iOS, and Vinyls. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of Doppler 2.3?
AssemblyAI— Speech-to-Text API with superhuman accuracy
Vinyls is a beautiful music player built with iOS design guidelines in mind. There are no complicated user accounts or settings to configure. You can start listening to your music right away. You can scrub to seek, watch the tone arm follow the playback time.
MusicSource is an open source and free desktop music player. It is served as a Progressive Web App so it requires no installation and is available offline. UI is a clone of YouTube Music but it is meant to play you own files. No server, no ads, no tracking.
Jams On Toast is a delightful music player for iOS, handcrafted for those who enjoy listening to albums. It is the only app that lets you rearrange your music in any way you'd like.