There is no easy way to know if an app is safe. Unfortunately, this means the idea that a “free market” will regulate errant apps is not presently workable as users have no way of knowing if an app is safe to use or not. Free markets require transparency to function well.
First, if an app or online service is “Free” for you to use, then you are the product. This is your first clue that your personal information is being harvested and sold to others.
Second, visit the app creator’s web site and read their About pages, and other pages about their business: Ask yourself, how does this company earn money?
Many app companies will describe their business model. When their business model is based on advertising, you need to be suspicious. Advertising today does not mean the old TV and radio model of advertising – you watch TV, they show you ads. In old-style advertising, known one knew anything about you individually.
However, in today’s smart device world (this applies to computers, smart phones, tablets and set top boxes, including Roku) all of your TV viewing and music listening is logged in someone’s database. Today, they are targeting ads at you, personally. Further, all of these connected devices are two way devices – that means your personal information is being sent to the content producers and advertisers. There is no obvious way to turn this off, in most instances.
Therefore, review the provider’s business model to gain an understanding in to how likely they are to be spying on you. If you are not comfortable with their spying on you, then look elsewhere.
Also learn how to read “Privacy Policies”
Privacy policies are actually anti-privacy policies designed to protect the company, not you!
Companies will disclose that they collect information, but typically write about it in obscure and confusing language without being specific. Their goal is to write a “weasel worded” policy that enables them to “weasel out” of any alleged offense about collecting end user information.
In other words, the Privacy Policy is an Anti-Privacy Policy that justifies their collection and use of most anything from you.