# Pyzed vs PyQt and PySide (Qt for Python)

> Pyzed vs PyQt6 and PySide6: license, size, look, programming model, designer and hot reload, with the same apps side by side, measured numbers and a guide to migrate Qt Widgets code to Pyzed.

Source: https://albakore.github.io/pyzed/why/vs-pyqt-pyside/

[Qt](https://www.qt.io) is the most complete GUI framework you can use from Python, through
[PySide6](https://doc.qt.io/qtforpython-6/) (by The Qt Company, LGPL) or
[PyQt6](https://www.riverbankcomputing.com/software/pyqt/) (by Riverbank, GPL or commercial). It has
everything: charts, multimedia, an embedded Chromium, 3D, printing, accessibility, and thirty years of
production use. That breadth comes with weight: a large download, a C++ object model (signals, slots,
parents, layouts) and licensing to think about.

## In short

| | Pyzed | PyQt6 / PySide6 |
| --- | --- | --- |
| License | MIT | PyQt: GPL v3 or commercial · PySide: LGPL v3 or commercial |
| Model | State + `view()`; plain Python callbacks | Object tree, signals and slots, or declarative QML |
| Look | Modern components and themes, out of the box | Native-like styles; modern looks through QSS or QML |
| Designer | Pyzed Design, generates Python | Qt Designer / Creator (`.ui` files), Qt Design Studio (QML) |
| Hot reload | `pyzed dev`, keeps state | QML preview in Qt tools; Widgets code needs a restart |
| Breadth | Desktop app essentials + IDE components | Almost anything, through dozens of modules |
| Mobile | – | PySide6 on Android (technical preview) |
| Accessibility | Keyboard; no screen readers yet | Full screen reader support |

## The same counter

## The same to-do list

In Qt Widgets you build the widgets once and keep them in sync with your data by hand (`refresh()` deletes
and recreates the rows). In Pyzed you only describe the rows for the current data.

## Measured

Medians from [the benchmarks](https://albakore.github.io/pyzed/why/benchmarks/) (Linux, no GPU: software rendering). The install size
for Qt is `pyside6-essentials` only; the full `pyside6` package with add-ons is several times larger.

## From Qt concepts to Pyzed

| Qt | Pyzed |
| --- | --- |
| `QApplication` + `QMainWindow` + `app.exec()` | `class MyApp(pz.App)` + `pz.run(MyApp)` |
| `QVBoxLayout`, `QHBoxLayout`, `QGridLayout` | `pz.column`, `pz.row`, `pz.grid` |
| `QLabel`, `QPushButton`, `QLineEdit`, `QCheckBox` | `ui.label`, `ui.button`, `ui.input`, `ui.checkbox` |
| `clicked.connect(slot)` | `on_press=method` |
| custom signals | messages sent to `update()`, or `pz.post(message)` from a thread |
| `QTimer` | `pz.every(...)` in `subscriptions()` |
| `QThread` / `QRunnable` | `async def` callbacks, generators, or plain threads |
| `QDockWidget`, `QTabWidget`, `QSplitter` | [`ui.workspace`](https://albakore.github.io/pyzed/library/workspace/), [`ui.tab_bar`](https://albakore.github.io/pyzed/library/tab-bar/), [`ui.split`](https://albakore.github.io/pyzed/library/split/) |
| `QTreeView` / `QTableView` + models | [`ui.tree`](https://albakore.github.io/pyzed/library/tree/), [`ui.table`](https://albakore.github.io/pyzed/library/table/), [`ui.virtual_list`](https://albakore.github.io/pyzed/library/virtual-list/) from Python lists |
| QSS stylesheets | [themes](https://albakore.github.io/pyzed/theming/themes/) and [`pz.Style`](https://albakore.github.io/pyzed/theming/styles/) |
| `QShortcut`, `QAction` | `on_key(combo)`, [commands](https://albakore.github.io/pyzed/guides/commands/) and `keys="ctrl-s"` on buttons |
| Qt Designer `.ui` files | [Pyzed Design](https://albakore.github.io/pyzed/editor/) `.pzform` files with Python handlers |

## Migration tips

1. **Start from the data, not the widgets.** List what your `QWidget` subclasses store (`self.items`,
   `self.current`…) and make those the attributes of your `App`. Everything that copies them into widgets
   (`setText`, `setChecked`, model resets) disappears.
2. **Turn slots into methods.** A slot connected with `clicked.connect(self.save)` becomes `on_press=self.save`.
3. **Replace models with lists.** A `QAbstractListModel` over a Python list becomes the list itself plus
   `ui.virtual_list` when it is long.
4. **Keep Qt where you depend on it.** If the app needs `QtWebEngine`, `QtMultimedia`, printing or 3D, Qt is
   still the right tool for that app.

## When to choose which

- **Choose Qt** when you need its breadth, a screen-reader-accessible app today, or decades-proven stability
  across a large team, and its size and license fit your project.
- **Choose Pyzed** when you want a modern-looking desktop app with far less code and ceremony, a permissive
  MIT license, a much smaller install, hot reload and AI assistance built into the workflow.