> what is the moat? Is it brand, speed of innovation, marketing, or something else?

You could try and develop a brand and market it but I don’t think that would go well for something like this. Best case maybe you can game the rankings to stay number one but you’re probably up against professional app copiers.

So your moat is speed of innovation. Your basic app is copied. What new feature will enable you to stay ahead and drive sales? Or perhaps no feature can do that as the crowd grows so it’s on to the next app that doesn’t yet exist. What’s your new pain point?

You're right that for a simple utility, brand can be a tough moat to build, and speed of innovation is definitely a huge part of the equation. My bet is that it's a combination of continuous innovation and a relentless focus on the user experience. The clones can copy a feature list, but it's much harder for them to copy a thoughtfully designed, native-feeling GUI and responsive customer support from a developer who is actually engaged.