Depending on what you're building, reddit is by far the best answer. For many things I've built I've been a part of the subreddit for a long time, intimately kn

Depending on what you're building, reddit is by far the best answer. For many things I've built I've been a part of the subreddit for a long time, intimately know the community, built something I know they need, and post it there. If it gets upvoted and they like it, its validated. If it doesn't get upvoted, well, back to the drawing board.