If you're looking for a djay alternative, Rekordbox is worth a look. The DJ software can link to several music streaming services and sync your library across up to eight devices. It can analyze tracks fast, sync your library to the cloud and optimize for mobile devices. It also supports a range of DJ hardware with compatible controllers and has a tiered pricing system with options for cloud library access from your DJ controller.
Another option is Fadr, a web-based service with a collection of AI-based music tools for music production and DJing. Fadr offers tools for removing vocals, splitting tracks, detecting key, tempo and chords, creating remixes and operating a DJ controller. Stem extraction is available for vocals, bass, drums and melodies, and there's a free version with basic features.
If you want to get more advanced with stem editing and audio processing, check out RipX DAW, an AI-based music production tool that lets you split mixed audio into stems, edit stems note by note, and replace instruments or vocals. Stem clean-up and audio repair tools are available in the PRO version, so RipX DAW should appeal to producers and DJs.
Last, Samplab is an AI-based polyphonic audio sample editor geared for DJs and music producers. It lets you edit notes and drums in polyphonic audio, detect and edit chords with MIDI file export, and automatically adjust tempo and key for seamless sample mixing. Samplab is available as a VST3 and AU plugin or desktop app, and there's a basic and premium version with a free trial.