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It's hard to tell why I'd use this and why I'd pay for this.

Edit: My review is based on my own profile – I would love to know how others would use this.

I admit that setting up build tools is cumbersome but with the amount of examples out there it has become more and more approachable. Plus, those tools are frequently updated which I wouldn't get through this app.

As a developer, I do not want to manually minify my code every time I make a change. I just want it done and I want it done well.

The amount of time spent manually using this app could be used up front to setup automatic builds.

Cloudflare has a feature that will bundle and minify your assets for you without configuring anything. It's not perfect by any means either but it'll do that automatically with asset versioning and all.

Implementing continuous integration with dozen of popular frameworks and CI services would be great. Actually, an app that create and maintain boilerplate code would be amazing.

I'd drop the dependency on the JVM and use JavaScript with a native wrapper since all the frontend build tools are written in JS and you could support other platforms.