Desktop: FreeTube. For Windows, Mac and Linux.
Android: LibreTube, NewPipe or NewPipe x SponsorBlock x Return YouTube Dislike (Fork).
Apple: Yattee. For iPhone, iPad, macOS and Apple TV (tvOS).
YouTube Music: Beatbump or Hyperpipe both are web versions.
Worth mentioning: Piped and CloudTube are both good alternatives to Invidious.
If you watch YouTube and don’t want Google watching back, this is the most mature option in the category by a wide margin, with desktop and mobile apps feeding off it. The real friction is that Google keeps breaking public instances, so the one you bookmark today may be rate-limited or dead next month. Self-host it if you want stability; otherwise accept that you will be instance-hopping and keep a backup or two handy.
Free to use, even commercially. Changes must be published under the same license, and running a modified version as a network service counts as distributing it.
Why it matters: The network clause is the point. Anyone who runs a modified version as a hosted service has to publish those changes, so the code handling your data stays inspectable. This is why privacy-first projects reach for AGPL.
Plain-language summary of the project's license, not legal advice. Read the full text for the exact terms.