Firebase

This one's battle-tested on dozens of shipped projects, and it shows. You get the full Firebase stack: auth, Firestore, Realtime Database, Cloud Functions, storage, and hosting. The angle here is brutally practical. Security rules are treated as non-negotiable from day one because someone learned the hard way. Data modeling focuses on Firestore's actual query limitations, not the marketing pitch. There's specific attention to the cost traps like attaching listeners to large collections. It pushes you toward denormalized, read-heavy patterns because that's what Firebase actually optimizes for. Good for anyone moving past Firebase tutorials into production territory where the easy setup stops hiding the complexity.