I'm not sure if React Native (I haven't done much with React on web pages) is on topic here but I would say without any hesitation authentication. React Native

I'm not sure if React Native (I haven't done much with React on web pages) is on topic here but I would say without any hesitation authentication. React Native is so good and so similar to front end web work (including integrating native libraries, it was downright joyful once I figured it out) that the experience of setting up the most basic email/password authentication scheme really stood out. This is true to some extent throughout the native landscape (that it's a little more complicated than web pages), but still. I think some might argue that this belongs in an external library, and maybe so, but I think there needs to be an easy to use standard library or framework component that keeps in mind what the developer experience is on the web. React Native is still my first choice for a small-medium native app project, a good authentication story would put it on another level. Also note the last time this came up for me was a year ago so maybe there has been improvement.