Typed state
Choose the scope that matches the lifetime: page, session, user, app, or client-only.
Public alpha · 0.1.0a2
Typed Python in.
Typed Python in.
Reactive web apps out.
Bretzel is a full-stack Python framework where the server owns the state and the browser follows—updating only the part of the page that changed.
The public Kanban board is isolated per browser session and resets periodically.
Python 3.12–3.13MIT licensedNo npm pipeline
class Counter(SessionState): value: int = 0 def increment() -> None: Counter().value += 1 @refreshable def count() -> None: ui.heading(str(Counter().value)) ui.button("+1", on_click=increment)
Counter changedOnly count() re-renders
100+public components
4 + 1server + client state scopes
10example applications
0JavaScript lines in the Kanban app
Mutation is the update API.
Declare what a region reads. Change typed state anywhere on the server. Bretzel finds the dependent region, renders it, and swaps that fragment in the browser.
Targeted regions
A region follows the state fields it reads, so updates stay local instead of rerunning the app.
One source of truth
No manual refresh call. No second client store. Mutating state is enough.
See it work.
Start with the live board, browse every component under the theme you pick, then explore the documentation and the source for all example apps.
Kanban board
Drag cards between columns, archive one, and try undo and redo.
Component gallery
Every component in real uses, with its Python code — and a theme studio that repaints them all.
Documentation
Follow the quickstart and inspect the components and drag-and-drop modes.
All example apps
The other examples are available to run from the repository.
One Python app.
A real web stack.
Rich components and server-driven HTML, without turning your application into a JavaScript build project.
Typed state→Declared dependency→HTML fragment→Browser swap
Updates across open windows
Declare broadcast= when an application should send state changes to other open windows over SSE. The public Kanban demo instead keeps each visitor's board in a separate session; its drag-and-drop, limits, and undo/redo work within that board.
Batteries included
Forms, overlays, navigation, data tables, server-rendered SVG charts, security headers, signed actions, OAuth/OIDC doors, and more.
Built to be inspected
bretzel describe exposes the exact API. bretzel check catches structural mistakes, including a deep application check.
Where Bretzel fits.
It sits between script-style app tools and a hand-built frontend: a Python-native application model with explicit state and targeted rendering.
vs NiceGUI
Bretzel does not keep a per-tab server-side UI object tree. Typed state and declared dependencies determine which HTML region is rendered and sent.
vs Reflex
Bretzel serves HTML fragments directly instead of compiling your Python app into React. There is no Node or Bun build pipeline to operate.
vs FastHTML
Bretzel adds a typed state model, targeted reactive regions, and 100+ integrated components on top of the server-rendered approach.
Early, useful, and honestly alpha.
Bretzel 0.1.0a2 is the latest public alpha. APIs may change, and the project currently has one maintainer. It is ready for people willing to build a small internal tool, find the rough edges, and shape the model with real feedback.
Take it for a spin.
Install the alpha, generate an app, and run it locally. Start small; bring back the confusing parts.
pip install bretzel