Pyzed vs Flet for Python desktop apps

Flet lets you build Flutter apps in Python. Your Python code runs in one process and sends the control tree to a Flutter client that draws it, on the desktop, on the web or on a phone. That reach is Flet’s big strength. Pyzed draws in the same process as your Python code, through a Rust renderer, and focuses on the desktop.

In short

	Pyzed	Flet
Architecture	One process: Python + Rust renderer (Iced)	Python process + Flutter client process, talking over a protocol
Platforms	Windows, macOS, Linux	Windows, macOS, Linux, web, Android, iOS
Look	Modern code-editor style, dense, desktop-first	Material 3 or Cupertino, mobile-first
Model	State + view() rebuilt from data	Mutable controls + page.update(); Flet 1.0 adds declarative components with hooks
Packaging	pyzed build (PyInstaller), no extra SDK	flet build (needs the Flutter SDK)
Designer	Pyzed Design	–
Hot reload	Keeps app state	flet run restarts the app on save
Accessibility	Keyboard; no screen readers yet	Screen readers through Flutter’s semantics

The same counter

Pyzed

"""Reference app: a counter with -, + and Reset."""

import pyzed as pz
from pyzed import ui


class Counter(pz.App):
    title = "Counter"
    size = (320, 200)

    def __init__(self):
        self.count = 0

    def add(self, step):
        self.count += step

    def view(self):
        return pz.center(pz.column([
            ui.heading(str(self.count)),
            pz.row([
                ui.button(icon="minus", on_press=lambda: self.add(-1)),
                ui.button(icon="plus", on_press=lambda: self.add(1), variant="solid"),
                ui.button("Reset", lambda: setattr(self, "count", 0), variant="ghost"),
            ], spacing=8),
        ], spacing=16, align="center"))


pz.run(Counter)

Flet

"""Reference app: a counter with -, + and Reset."""

import flet as ft


def main(page: ft.Page):
    page.title = "Counter"
    page.window.width, page.window.height = 320, 200
    count = ft.Text("0", size=24)

    def change(step):
        count.value = "0" if step is None else str(int(count.value) + step)
        page.update()

    page.add(ft.Column([
        count,
        ft.Row([
            ft.IconButton(ft.Icons.REMOVE, on_click=lambda e: change(-1)),
            ft.IconButton(ft.Icons.ADD, on_click=lambda e: change(1)),
            ft.TextButton("Reset", on_click=lambda e: change(None)),
        ], alignment=ft.MainAxisAlignment.CENTER),
    ], horizontal_alignment=ft.CrossAxisAlignment.CENTER))


ft.run(main)

The same to-do list

Pyzed

"""Reference app: add tasks (button or Enter), tick them off, delete them, see how many are left."""

import pyzed as pz
from pyzed import ui


class Todo(pz.App):
    title = "To-do"
    size = (420, 480)

    def __init__(self):
        self.tasks = []  # [title, done]
        self.draft = ""

    def add(self):
        if self.draft.strip():
            self.tasks.append([self.draft.strip(), False])
            self.draft = ""

    def toggle(self, task, done):
        task[1] = done

    def row(self, task):
        return pz.row([
            ui.checkbox(task[1], lambda done: self.toggle(task, done)),
            ui.label(task[0], color="text_muted" if task[1] else "text", width="fill"),
            ui.icon_button("trash-2", lambda: self.tasks.remove(task)),
        ], spacing=8, align="center")

    def view(self):
        left = sum(not done for _, done in self.tasks)
        return pz.column([
            ui.heading(f"{left} left", level=3),
            pz.row([
                ui.input(self.draft, lambda text: setattr(self, "draft", text), on_submit=self.add),
                ui.button("Add", self.add, variant="solid"),
            ], spacing=8),
            pz.scrollable(pz.column([self.row(t) for t in self.tasks], spacing=4), height="fill"),
        ], spacing=12, padding=16)


pz.run(Todo)

Flet

"""Reference app: add tasks (button or Enter), tick them off, delete them, see how many are left."""

import flet as ft


def main(page: ft.Page):
    page.title = "To-do"
    page.window.width, page.window.height = 420, 480
    tasks = ft.Column(scroll=ft.ScrollMode.AUTO, expand=True)
    left = ft.Text("0 left", size=18, weight=ft.FontWeight.BOLD)

    def refresh(_=None):
        left.value = f"{sum(not row.controls[0].value for row in tasks.controls)} left"
        page.update()

    def remove(row):
        tasks.controls.remove(row)
        refresh()

    def add(_):
        if entry.value.strip():
            row = ft.Row([ft.Checkbox(label=entry.value.strip(), on_change=refresh, expand=True)])
            row.controls.append(ft.IconButton(ft.Icons.DELETE, on_click=lambda e: remove(row)))
            tasks.controls.append(row)
            entry.value = ""
            refresh()

    entry = ft.TextField(expand=True, on_submit=add)
    page.add(left, ft.Row([entry, ft.Button("Add", on_click=add)]), tasks)


ft.run(main)

Measured

Medians from the benchmarks (Linux, no GPU: software rendering for both). Flet’s memory includes its Flutter client process, which is where the window lives. Its install size counts the Python packages plus the desktop client that flet downloads on first run.

Measurement (lower is better in every row)	Pyzed 1.2.0	Flet 1.0.4
Import the library	35 ms	40 ms
First frame, 10 rows	165 ms	579 ms
First frame, 1,000 rows	243 ms	994 ms
Memory (RSS), 10 rows	151 MB	268 MB
Memory (RSS), 1,000 rows	161 MB	395 MB
Update 1,000 rows	18 ms	166 ms
Lines: counter	19 lines	17 lines
Lines: to-do list	31 lines	22 lines

From Flet concepts to Pyzed

Flet	Pyzed
ft.run(main) with main(page)	pz.run(MyApp) with a pz.App class
page.add(...), page.update()	return the tree from view(); no manual update
ft.Column, ft.Row, ft.Container	pz.column, pz.row, pz.container
ft.Text, ft.Button, ft.TextField, ft.Checkbox	ui.label, ui.button, ui.input, ui.checkbox
on_click=handler(e)	on_press=method (no event argument needed)
page.theme_mode = ft.ThemeMode.DARK	theme = "One Dark" or pz.themes.auto(...)
page.run_task(coro)	return a coroutine from a callback
ft.ListView	ui.virtual_list
ft.NavigationRail, ft.Tabs	ui.workspace panels, ui.tab_bar

Migration tips

1. Move control state into the app. Values you read back from controls (field.value, checkbox.value) become attributes, set by the controls’ callbacks.
2. Delete page.update() calls. Pyzed redraws after every callback.
3. Expect a denser UI. Material spacing is made for touch; Pyzed’s components are sized like a desktop editor. Use size="lg" variants or styles if you want more air.

When to choose which

• Choose Flet when one codebase must run on the web and on phones, or you want Flutter’s Material widgets.
• Choose Pyzed for desktop-first apps: one process, no Flutter SDK to package, a visual designer, hot reload that keeps your state, and a dense, professional look.