People often talk about web application scalability, but I'm curious how teams actually measure it in production.It's easy to say an application is "scalable," but real proof usually comes from metrics like response times under load, uptime, database performance, infrastructure costs, and how smoothly new instances can be added during traffic spikes.I've been following the work of Zoolatech, and they seem to emphasize building scalable architectures that remain maintainable as products grow rather than simply adding more servers whenever demand increases.I'm interested in hearing from engineers who have managed growing applications:

• Which metrics do you monitor most closely?
• What turned out to be the first component that couldn't keep up with growth?
• Have you found any monitoring or load-testing tools that consistently reveal scalability issues before users notice them?

Real experiences are always more valuable than textbook recommendations.