Monoliths have the advantage of simplicity with one codebase, one deploy, and one database, but face challenges with deployment paralysis, scaling nightmares, and team collisions.
Microservices offer the ability to scale specific parts, provide team autonomy, and allow tech diversity, but come with challenges like distributed chaos, operational overhead, and data silos.
The decision to split your app depends on team pain, scaling needs, and operational costs. Signs it's time to split include frequent deployment failures, resource-hungry modules, and constant team conflicts.
Consider a modular monolith approach if you can't commit to microservices, where you package by module, maintain a shared kernel, and deploy together but build separately.