libxev is a cross-platform event loop. libxev provides a unified event loop abstraction for non-blocking IO, timers, signals, events, and more that works on macOS, Windows, Linux, and WebAssembly (browser and WASI). It is written in Zig but exports a C-compatible API (which further makes it compatible with any language out there that can communicate with C APIs).
Project Status: 🐲 Unstable, alpha-ish quality. The feature list is quite good across multiple platforms, but there are plenty of missing features. The project hasn't been well tested in real-world environments and there are lots of low-hanging fruit for performance optimization. I'm not promising any API compatibility at this point, either. If you want a production ready, high quality, generalized event loop implementation check out libuv, libev, etc.
Why a new event loop library? A few reasons. One, I think Zig lacks a generalized event loop comparable to libuv in features ("generalized" being a key word here). Two, I wanted to build a library like this around the design patterns of io_uring, even mimicking its style on top of other OS primitives ( credit to this awesome blog post). Three, I wanted an event loop library that could build to WebAssembly (both WASI and freestanding) and that didn't really fit well into the goals of API style of existing libraries without bringing in something super heavy like Emscripten. The motivation for this library primarily though is scratching my own itch!