Vercel open-sources fx, a blazing fast native coding agent
evilrabbit_ · x · 2026-08-21
Vercel Labs has open-sourced fx, an internal coding agent harness and CLI written in Zig. It is built on three principles:
- Fast: Cold starts in 10µs with a single native binary and no runtime.
- Light: The 6.3MiB binary uses single-digit MBs of RAM, designed for embedding in resource-constrained environments.
- Open: Apache-2.0 licensed, model and provider agnostic.
A demo shows fx running inside a Vercel function using just-bash as an in-memory filesystem.
Related event: Vercel Open-Sources fx, an Ultra-Lightweight Coding Agent(3 posts)→
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