more important: can I upload tracks to Spotify?
Worth checking out this thread…
Also, there are many articles online reviewing and comparing options/services…
I find a helpful article, which covers the ways to add local files to Spotify, you can visit it to see it can work well for you here: How to Add Local Files to Spotify
Besides, Spotify allows free users to do this. No need to upgrade to Spotify Premium, you can upload tracks to Spotify.
To be clear, that isn’t really uploading files to Spotify.
It’s a way to use Spotify as a music player app for your local files, including making them available on your mobile devices.
Only you will be able to play those local files.
Amuse.io has always been a good option, they’ve changed a few things as of late but it still works nicely
I find another article: How to Add Local Files to Spotify
Is this also a way to use Spotify as a music player app but not truly upload files to Spotify?
I mostly use it for all the unfinished/unpublished tracks I’ve created.
It’s a handy way to have it on your phone to listen to actively/passively while you think about how to develop, tweak or finish it.
(Though I think the OP was talking about releasing on Spotify, rather than as a ‘player’.)