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Philosophy

Why moon-spa exists​

Modern frontend development has drifted toward enormous complexity: JavaScript bundlers, transpilers, virtual DOMs, state management libraries, and megabyte-sized bundles — all to display a web page.

moon-spa asks: what if Python handled it all?

Core beliefs​

Python is a great frontend language​

Python's readability and expressiveness make it ideal for UI logic. setup(self, props) unifies server data (data) and reactive behavior (state/actions/lifecycle) in one contract. No JSX, no TypeScript generics, no useEffect dependency arrays.

SSR should be the default, not the exception​

Server-rendered HTML is fast, SEO-friendly, and accessible. JavaScript should enhance an already-functional page, not be required to show any content at all.

No build step is a feature​

Every extra tool in the chain is a point of failure, a configuration burden, and an onboarding obstacle. moon-spa ships the runtime inside the package. pip install is the entire setup.

Constraints enable clarity​

By restricting client logic to Python-declared specs, moon-spa can:

  • Generate optimized JavaScript automatically
  • Validate component contracts at load time
  • Make components fully readable without executing them

What moon-spa is NOT​

  • A full React/Vue replacement for complex client applications
  • A server framework (it's a SPA layer — pair it with FastAPI, Flask, etc.)
  • A UI component library (it's a rendering engine)
  • Production-ready for high-traffic applications without an external WSGI server

The name​

moon (Portuguese for moon) — lightweight, reflected light from a larger body.
spa — Single Page Application.

A minimal SPA framework that reflects Python's simplicity.