zigfetch

A neofetch-style system info display compiled to WebAssembly (WASI), running inside a browser terminal. Built with Zig — the same binary works natively on Linux and as a WASM module in the browser.

Screenshots

Web (Brave)

Linux (Debian)

---

Features

Field	Linux	Browser
󰋜 OS	/etc/os-release	Browser name (Brave, Chrome, Firefox…)
󰍛 RAM	sysinfo syscall	WASM module memory
󰗊 Lang	$LANG env var	navigator.language
󰍹 Res	xrandr	screen.width x screen.height
󰻠 CPU	/proc/cpuinfo	navigator.hardwareConcurrency
󰖟 Host	gethostname()	location.hostname
󰢮 GPU	glxinfo -B	WEBGL_debug_renderer_info

---

How It Works

The project compiles a single Zig codebase to two targets:

zig build                              # Native Linux binary
zig build -Dtarget=wasm32-wasi         # WASM module for the browser

In the browser, the WASM module runs inside a Web Worker with a custom WASI implementation. System info that requires browser APIs (resolution, GPU, language) is captured from the main thread and injected into the WASM module via extern "env" function imports.

terminal.js (main thread)
  │  captures: screen, GPU, navigator.*
  │  postMessage → 
  └─ wasi_worker.js (Web Worker)
       │  implements: WASI syscalls + env imports
       └─ zigfetch.wasm
            │  calls: getBrowserName(), getResolution(), getGpu()...
            └─ prints via fd_write → postMessage → xterm.js

---

Project Structure

src/
├── main.zig              # Entry point and render loop
├── info/
│   ├── os.zig            # Linux OS name from /etc/os-release
│   ├── ram.zig           # RAM via sysinfo (Linux) or @wasmMemorySize
│   ├── browser.zig       # extern "env" imports from JS host
│   └── system.zig        # Linux: language, resolution, GPU, hostname
└── render/
    └── logo.zig          # Color palette renderer

public/scripts/
├── terminal.js           # xterm.js shell, captures browser info
└── wasi_worker.js        # WASI runtime implementation in JS

---

Requirements

To build

• Zig 0.13

Optional (Linux native, for full info)

• xrandr — screen resolution
• glxinfo (mesa-utils) — GPU renderer

Browser requirements

• SharedArrayBuffer support (requires COOP/COEP headers)
• Chromium-based browser recommended for WEBGL_debug_renderer_info

---

Building

# Native Linux binary
zig build -Doptimize=ReleaseSmall

# WASM module for the browser
zig build -Doptimize=ReleaseSmall -Dtarget=wasm32-wasi

# Run locally
./zig-out/bin/zigfetch

# Test WASM with wasmer
wasmer zig-out/bin/zigfetch.wasm

---

Serving in the Browser

The site must be served with these HTTP headers for SharedArrayBuffer to work:

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Opener-Policy: same-origin

Without these headers the terminal will display an error instead of loading.

---

Browser Compatibility

Browser	OS Name	GPU Renderer	RAM
Chrome / Edge	✅	✅	⚠️ performance.memory (approx)
Brave	✅	✅ (unblocked)	❌ blocked by anti-fingerprint
Firefox	✅	❌ blocked?	❌ blocked?
Safari	✅	❌ blocked?	❌ blocked?

GPU info and RAM availability depend on the browser's privacy settings. Fields show graceful fallbacks when unavailable.

---

Adding New Fields

1. Capture in terminal.js (if the API is main-thread only):

const myValue = someMainThreadAPI();
worker.postMessage({ ..., myValue });

2. Expose in wasi_worker.js:

const { myValue } = e.data;
// in env:
getMyValueLen: () => myValue.length,
getMyValue: (ptr) => { /* write to WASM memory */ },

3. Declare extern in src/info/browser.zig:

extern "env" fn getMyValueLen() u32;
extern "env" fn getMyValue(ptr: [*]u8) void;

pub fn getMyValue(allocator: std.mem.Allocator) []const u8 { ... }

4. Add Linux fallback in src/info/system.zig and wire both in main.zig.

---

License

MIT