About fx

fx is a tiny, open, native coding agent for the terminal: a coding agent harness and CLI written in Zig, optimized for research and embeddability as part of larger systems. It is open source under Apache-2.0, model-agnostic, and suitable for both local and cloud inference.

The binary is around 6mb and starts in microseconds. Its output style aims to be closer to a Unix shell than to an IDE in the terminal. The same core ships as a library: libfx on npm embeds fx in Node.js or WebAssembly hosts.

Who builds it

fx is built by Vercel Labs, the group at Vercel Inc. that develops open source and experimental projects. Development happens in the open: source, issues, and releases live at github.com/vercel-labs/fx.

Where to go next

The documentation covers installation, configuration, and everything fx can do. The changelog tracks each release. You can try fx in the browser without installing anything, and the contact page lists the right channel for bugs, security reports, and privacy questions.