Welcome to Wren

Wren is a web browser written from scratch in Odin. Its JavaScript engine is its own, compiled to WebAssembly and run in a sandbox: one instance per page and per worker, with a capped heap and a deadline on every call. A page can also be a single .wasm file that calls the browser directly, no JavaScript at all. Style, layout, painting, the DOM and the network are new code; there is no Chromium underneath.

Download Wren 0.6.28 for Windows x64 or Linux x86-64 (an early preview, free during the beta; PolyForm Strict license)

What works

Documents and CSS-heavy sites, within a few percent of Edge pixel for pixel.
Sites whose scripts add to the page: menus, themes, web components, observers.
WebAssembly pages with the DOM, events, timers, fetch, WebSocket, workers and storage.

What doesn't, yet

JavaScript is interpreted, with a JIT for numeric loops only, so script-heavy pages are slow.
About 72 % of the members of the web platform's Web IDL are implemented; no WebGPU or WebRTC, WebGL without transform feedback.
Linux needs glibc 2.39 or later, and decodes video in software for now.

Some numbers

1.4	ms	CPU to wheel-scroll 10,000 paragraphs (99th percentile, under the 5.56 ms of a 180 Hz frame)
2.3	ms	GPU for the same
1.3	ms	for a page's JavaScript to start
7	ns	a call from WebAssembly into the browser (58 modules, 1,482 functions)
0.3	s	from launch to the start page drawn

Measured on the development machine. The rest is in the features, the changelog and the architecture notes.