2026-01-10 flutter python

Flet in 2026: Flutter UI, Python logic, and the trade-offs you need to admit upfront

Flet lets you build Flutter UIs with Python logic. Here are the real trade-offs: latency from event chatter, ecosystem mismatch with Dart plugins, and split-brain debugging -- plus when it actually makes sense.

A r/FlutterDev thread resurfaced Flet as “build Flutter apps in Python”. It’s not a new idea, but it’s a persistent one because the motivation is real: a lot of teams have deep Python expertise and want a cross-platform UI without adopting Dart on day one.

Sources: the Reddit thread and flet.dev.

What Flet is (and what it is not)

Flet is not “Python that compiles to Flutter”. The common model is:

A Flutter front-end that renders UI.
A Python runtime that executes your app logic.
A protocol that syncs UI events and state (often JSON over WebSockets).

That distinction matters because it changes the performance and debugging story. You’re effectively building a distributed app, even when it runs on your laptop.

A tiny example you can run and reason about

import flet as ft

def main(page: ft.Page):
    page.title = "Start Debugging: Flet demo"

    name = ft.TextField(label="Name")
    out = ft.Text()

    def greet(e):
        out.value = f"Hello, {name.value}"
        page.update()

    page.add(name, ft.ElevatedButton("Greet", on_click=greet), out)

ft.app(main)

If you’re a Python developer, this is the hook: you get a UI fast and you stay in the Python ecosystem for business logic and libraries.

The trade-offs vs writing Flutter directly (Dart 3.12, Flutter 3.x)

You pay for the convenience in places that matter in production:

Latency and event chatter: UI interactions become messages. It can be fine for forms and dashboards, but it’s a different profile than pure Flutter.
Ecosystem mismatch: Flutter plugins and packages are designed for Dart. Bridging native APIs from Python can be awkward, especially on mobile.
Debugging split-brain: Flutter DevTools and Dart-level profiling do not automatically surface Python-side bottlenecks.

None of this makes Flet bad. It just makes it a different product: Flutter-rendered UI with Python semantics.

When I would pick Flet

Internal tools where time-to-first-UI is the main constraint.
Desktop and web targets first, mobile later.
Teams with strong Python competence that need a UI surface, not a “Flutter-first” engineering culture.

If you’re building a consumer mobile app where frame timing, plugin depth, and native debugging matter, I still reach for Flutter directly. Flet is interesting because it lowers the entry barrier, but you should be explicit about what you’re trading away.