Twitter: Find testers using the common hashtags #Betatesting #Betatesters #Testmyapp #Indiedev, or scout for potential testers by checking several public Twitter lists that have been compiled by other apps.Reddit: There are specific subreddits to help you find beta testers. Here are a few: /r/TestMyApp, /r/alphaandbetausers and /r/AndroidAppTesters.Betali.st: One of the most active websites to find new betas. They feature two to 10 new startups every day.Erli Bird: The focus here is around getting qualitative feedback for your app. You have the option of listing your startup as pre-launch, private access (with promo code), or a paid focus group.Quora: Most early adopters and influencers can be found answering questions on Quora, so make sure to signNow out to them, engage with them, and get their feedback about your app.StartupLi.st: Similar to http://Betali.st, but listings are controlled and edited by yourself. You create an account and can edit your startup listings.Betatesters.io: Simple, straightforward, easy to use. Powered by Instabug.Hacker News: HN’s community loves to try new things. That’s a great opportunity to get expert feedback from a very tech-savvy audience. Submit your app to ShowHN, but make sure to follow the rules.Beta Bound: Developed by Center Code to collect, organize, and offer beta testing opportunities in an ongoing stream.TNW Market: You can create a listing of your startup for free and people can choose to sign up to be part of your beta testers team.Beta Family: Beta Family is a crowd testing platform for beta testing iOS and Android applications. You can test apps on real people and get an honest opinion on the user experience.AppStorm: A web and mobile channel where apps get reviewed. To get your app accepted, you will need to have a great presentation.Killer Startups: Killer Startups is a news site that accepts submissions for review.In addition to this list, you can also hunt for potential testers by joining communities on Google+, Facebook, LinkedIn, and any relevant blogs. Simply reply to a relevant post, talk about your app and how it provides a solution to the problem stated in the topic, and ask people to check it out. This technique could get you sincere testers if you play it right and only post relevant comments.Hope this helps! Get answers to all your beta testing questions and more tips and resources in this comprehensive Slideshare presentation by Instabug (where I work): The Ultimate Beginner’s Guide For Beta Testing Mobile Apps