They offered a version of the YouTube client which they patched to remove display ads and video ads, plus add background play, SponsorBlock support, and more.
They became fairly popular before Google shut them down for distributing modified versions of their proprietary code.
ReVanced was one of the teams that popped up in the aftermath, a spiritual successor. They reasoned that they could achieve the same basic functionality legally if they only distributed patches (instructions) rather than a pre-patched binary.
So they wrote an app (ReVanced Manager) that takes a stock copy of the YouTube app, unpacks it, applies patches, then repacks & re-signs it. (They don't have Google's signing keys, so typically users need to install the new version under a new name. Users with root can choose to override the built-in version instead.)
Once ReVanced Manager could do that, they expanded into patching other apps as well.
So ReVanced is a team that maintains:
* A list of useful patches
* An engine to apply them
* A Java CLI frontend to the patcher
* An Android app frontend to the patcher
Yeah, they can. By which I mean, they can do it right away, for the official Reddit app:
– https://revanced.app/patches?pkg=com.reddit.frontpage
– https://revanced.app/download
Or, for even less work, you can just use a pre-patched APK with the ads removed: https://github.com/revanced-apks/build-apps/releases
No need for root access nor flimsy DNS solutions.