When you need a runtime
SSR Next.js, any Node server (Express, NestJS, Fastify), any Python WSGI/ASGI app (Django, FastAPI, Flask), Streamlit and Gradio — for applications with a long-lived process.
The stateless invariant
A runtime container's filesystem is ephemeral. What does NOT work (writing to SQLite, file-based sessions) and how to do it properly.
Lifecycle & speed
Layero's serverless model: warm responses in ~0.2 s, cold starts of 4–12 s depending on the stack, freeze on idle. Real measurements and what they mean for your app.