Please DO NOT build a large application on raw Vertx. Quarkus gives you things like auto generated openapi specs etc.

Quarkus is just compile time stuff around vertx, and you write simple synchronous code. Again, DO NOT use vertx directly for building APIs. It'd be like using just expressjs and writing your api specs manually... in 2025...

No capitals needed. I have written many backend services around raw Vertx very successfully. It's simple, well documented and predictable, mainly because everything is done in code.

Deviating from Quarkus's standard behaviour was comparatively difficult, either tracking down the correct configuration properties and what to change them to, or which api to implement and override and what it needs to do.

I prefer to develop OpenAPI specs separately from the code too, mainly because it's a joint effort with other teams. Vertx can incorporate them easily.