Reddit has a magic quality to it. There are a ton of groups. Some of the groups I have used so far are Betatesters, Buildinpublic, Earlystageapps, Indiehackers

Reddit has a magic quality to it. There are a ton of groups. Some of the groups I have used so far are Betatesters, Buildinpublic, Earlystageapps, Indiehackers, Sideproject, Startup Ideas, Y Combinator. There are also specific groups like Public Domain and Borges which I posted my app to. Some of the other social media Like LinkedIn and here have helped as well.