fx: A 6 MiB Zig-Native Open-Source Coding Agent That Runs in the Browser
cramforce · x · 2026-10-30
fx is a tiny Apache-2.0 coding agent harness and CLI written in Zig — a 5.97 MiB model-agnostic binary designed for research and embedding, with a shell-like terminal UI.
- The poster discovered fx caps the number of sub-agents you can spawn
- fx ask runs single requests with no background service; suitable for terminals, CI, and agent sandboxes
- Ships a WebAssembly demo compiling the full CLI into the browser (JSPI required), with networking delegated to browser fetch
- Concise tool schemas keep context small; skills and MCP tool schemas load on demand; embeddable via libfx with custom tools and MCP servers
Related event: Vercel Open-Sources fx, a Tiny Zig Coding Agent(2 posts)→
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