Tiny, open, native coding agent.
v0.0.36.39mib status: experimental use at your own risk, we will be making frequent changes
𝒇x v0.0.3 · Run /help for commands
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auto · glm-5.2
Install fxfor the full tool suite on your own files.
fx is a coding agent harness and CLI written in Zig, optimized for research and embeddability as part of larger systems.
It focuses on minimalism and performance across the board, from system prompt design, to its tools, feature set, and 6.39mib binary.
For end users, its CLI output style and form factor aims to be closer to a Unix shell than a heavy "IDE in the terminal" TUI.
It's open source (Apache-2.0), model-agnostic, and suitable for both local and cloud inference.
Tiny ~6mb binary #
Designed for instant installation and embedding in resource constrained environments and agent sandboxes.
Instant time to prompt #
fx cold starts in 10µs and does no unnecessary work or I/O prior to accepting user input, making it ideal for programmatic use.
Wasm support #
Optimal fx.wasm builds produced by the Zig toolchain, which further reduce fx's size, making the network stack pluggable.
Minimal memory footprint #
fx contributes single-digit megabytes of memory baseline, allowing you to pack many instances in one machine.
Shell-like UI and ergonomics #
fx preserves scroll history by default, produces minimal output, and makes sparing use of complex TUI or paints
Context efficient #
Minimal system prompt and tools, to save on token costs and to yield optimal time-to-first-token performance (TTFT).
Embeddable and extensible #
Small core, extended via skills, plugins, MCPs, with a Unix-like philosophy to extensibility.
Model and provider agnostic #
Designed to work with local models, gateways, direct provider API access or subscriptions.