Yes, SEO can bring free traffic to an app. ASO is somewhat similar to SEO. SEO is done to get our websites on the front pages of search engines,similar ASO for our apps. When mentioned increase app users, app store optimization is a good way, too. After do app store optimization, app’s visibility can be increased and then get more app downloads. More app downloads an app get, more downloads it will get. So this is a good way to gain new users. When an app have a large user base, it will come in the top when users search the keywords in the search box. So do a good ASO can help increase new users. If app developers have enough budget, I recommend they cooperate with some professional companies, such as ASOTOP1. They guarantee they can help boost App Store Ranking via App Store Optimization and Get App Ranked in Search Results. So your app will get a lot of new users.