gosub-io/gosub-engine

Gosub is a browser engine, which is the core software that sits underneath a web browser and handles loading web pages, parsing HTML and CSS, running JavaScript, and drawing the result on screen. Most people interact with finished browsers like Chrome or Firefox, but Gosub is the engine layer that a developer could embed inside their own application or custom browser shell rather than building everything from scratch. The project is written in Rust and is organized into distinct pieces: one part handles HTML parsing, another handles CSS, another manages network requests, another does page layout, and there are separate rendering backends for different graphics systems. This modular design means you can swap out the renderer or connect your own interface on top. The engine also supports running multiple tabs simultaneously, with each tab having its own isolated cookies and local storage. As of now, Gosub can parse HTML and CSS according to web standards, fetch resources over the network, and manage multiple tabs through an event-based interface. Full pixel-perfect rendering and complete JavaScript execution are still in progress. The project also compiles to WebAssembly, which means it can in theory run inside a web browser itself, demonstrated by a screenshot in the README showing a browser running inside another browser. Gosub is an open project welcoming contributors and is under active development. The team coordinates through Zulip and Discord chat. If you are a developer curious about how browsers work internally, or someone building a tool that needs a programmable web-page renderer without shipping a full browser binary, this project is worth watching. Setup requires Rust's standard toolchain, and GTK4 libraries are needed only for the graphical demo examples.