pysx-framework 0.7.0

Reactive interfaces, written in Python.

PYSX brings the feel of a reactive web app to Python. Write your interface with readable, indentation-based templates, keep state in signals, and let the page update as that state changes.

Python runs on the server. A small JavaScript client connects the browser to your application, sends user events, and applies the updates it receives.

Install

Use Python 3.14 or newer and install pysx-framework from PyPI:

python -m pip install 'pysx-framework==0.7.0'

Or add it to a uv project with uv add 'pysx-framework==0.7.0'. The Python import remains pysx. Follow the quickstart to run your first application.

How it works

The initial HTTP response contains the rendered page. The browser attaches to that same graph, preserving edits made before attachment. Each session gets its own reactive state. Signals hold values, derived signals compute from them, and effects track dependencies automatically. When a user clicks a button or edits a field, Python handles the event and sends changes back to the page.

Templates use Python 3.14+ t-strings to keep markup and live values together:

Changing count updates the displayed value. The browser applies targeted patches, and keyed lists preserve unchanged rows so focus, selection, and scroll survive updates.

Build with PYSX

• Reactive state: signals, derived values, batched updates, and writable views into structured data.
• Readable interfaces: t-string templates and composable, typed native elements.
• Live forms: two-way bindings, native validation, reset and submit handling, and caret-preserving server corrections.
• Async applications: owned resources, timers and server push update pages without another browser event.
• Document continuity: open pages restore compatible UI state after server loss. See recovery.
• Hosting: shared standalone and optional ASGI serving, request context, static assets and lifecycle hooks. See hosting.
• Scoped styling: typed styled bases, inherited rules, live CSS variables and isolated themes. See the styling guide.
• Editor support: VSCode syntax highlighting and advisory template diagnostics.

Playgrounds

Copy runnable starter applications into your own project, then run them the ordinary way:

pysx-playground                        # all of them, into ./playgrounds
pysx-playground counter                # just one
pysx --app playgrounds.counter         # run it
pysx --app playgrounds.counter --watch # edit the file and watch it reload

counter is the smallest useful live application, recovery a draft that survives a restart with the tab open, and durable declared state reconstructed through a fresh application graph. Re-running pysx-playground <name> restores that playground to its shipped source and clears its state, so it is also the reset.

Supported platforms

Python 3.14 or newer. The quality matrix has passed on Linux, macOS and Windows. See compatibility and support for tested versions, deployment requirements and maintenance windows.

PYSX is available under the MIT license.

Explore

Start with the quickstart, work through the interactive tutorial, or browse the API index.

• Examples — run the demos and explore reactive state and live forms.
• Tests — run the test suite and quality checks.
• Editor support — install the VSCode extension.

For the technical details, see the template grammar, native elements and bindings, and wire protocol.