When should you not use Node.js?

Node.js is awesome for I/O-heavy, real-time apps, but it’s not ideal for:

• CPU-intensive tasks: Heavy computations block the event loop and slow down all

requests.

• Applications requiring multithreaded parallelism: Though worker threads exist,

Node.js is not designed for parallel CPU-heavy workloads by default.

• When you need mature libraries for complex domains: Some domains (like

machine learning) have better ecosystems in other languages.