Gallery
Python apps, in the browser, measured.
Python in the browser, on its own runtime compiled to WebAssembly. Every app below is a directory of static files: no server, no build step, no JavaScript toolchain. The numbers are measured, not claimed — they come from loading each page in Chromium with a cold cache.
Counter
Signals, a memo, and a hole that updates one text node.
Todo
A store, a keyed For, two-way binding.
Template
The same counter written as html(t"…").
Forms
Bindings, Switch, an Action on submit.
Fetch
Resource, Loading and Errored.
Contacts
The router: nested routes, links, query strings.
Lazy route
A route in a chunk of its own: fetched on hover, not on load.
uPlot
A JavaScript chart library as a component — 20,000 points on a canvas.
Wasm library
A WebAssembly library imported like any Python module.
Your own Rust
A 1 KB Rust library, called from Python: 13× on the arithmetic.
Spectrum
An FFT, a spectrogram and a filter, in 12 KB of Rust. No server.
Weather
Streamlit's Seattle Weather demo, ported: five charts, no server.
GW150914
Streamlit's GW Quickview, ported: real LIGO strain, whitened in the page, the merger found.
Uber NYC
Streamlit's flagship demo, rebuilt: a million pickups, and panning the map is an input.
Tracker
The whole framework in one app: routes, store, optimistic writes, a portal.
Islands
A static page and two islands: the runtime is not on the critical path.
Blog
Markdown, front matter and a schema — rendered at build time, with an island in the prose.
Site
A directory of pages as a directory of files: posts, an endpoint, an island. The card is its front page.
Measured 2026-10-07 · Chromium, cold cache, first paint of the app's own content · the interpreter, the loader and the framework are 853 KB of every figure and are byte-identical, so a browser downloads them once for all of them. A card marked no runtime is a static page with islands: it was measured with the runtime denied, so its figure is the page, its stylesheet and the 1.3 KB loader — the runtime arrives later, when an island's trigger fires, or never.