Fern

A small, fast-startup language for CLI tools and edge HTTP servers.

Get started Try in browser Source on GitHub

Fern is a small, statically-typed compiled language. One source compiles to lean CLI binaries and tiny wasm edge modules across arm64 (Linux + macOS), x86-64, and WebAssembly.

Fast-startup binaries

Native arm64 + x86-64 ELF, no runtime, no GC. Link statically, start in milliseconds.

WebAssembly ready

WASI Preview 2 component output. Drop the .wasm into wasmtime or any host — no glue code.

Real editor support

fern-lsp ships hover, goto-definition, completion, signature help, inlay hints, rename, format-on-save, and a VS Code extension.

Type-checked

Sized integers, monomorphised generics, tagged-union enums with exhaustive matching, Option and Result built in.

Hello, world

open in playground →

Where next

Tutorial — install the toolchain and learn the language one concept at a time.
Reference — syntax and type system docs.
Standard library — every std/* function with signatures and examples.
Playground — try Fern in your browser, no install.