If you need a tool that separates vocals from instrument tracks in an audio file without having to install any software, Vocali.se is a good option. The web-based service uses machine learning and artificial intelligence technology to isolate vocals from music tracks, a process that's fast and relatively accurate. You can upload a variety of audio file formats and then download the resulting files, which makes it good for karaoke versions or for isolating audio elements.
Another option is Cryo Mix, an AI-powered music mixing and mastering service. It's got an AI Audio Separator tool that isolates stems like vocals, drums and instruments from a single audio file. It's part of a larger suite of tools to tweak and polish audio, including tools for correcting pitch and balancing EQ.
If you want a more general-purpose tool, Fadr offers a range of AI-powered music tools, including a vocal remover. Stem extraction tools can separate different audio elements, and remix tools let you try out different combinations. It's a good option for musicians and music producers. It offers both free and paid levels of service, so you can pay for what you need.
Last, Media.io is a general-purpose media processing service with an AI Vocal Remover among many other tools. It's geared for content creators, with a drag-and-drop interface that's easy to use even if you're not a techie. It can handle a variety of file formats, and there's a free trial level with limited abilities.