The problem we kept running into: existing CLI frameworks in the JS ecosystem are either minimal arg parsers where you wire everything yourself, or heavyweight frameworks with large dependency trees and Node-era assumptions. We wanted something in between.
What Crust does differently:
- Full type inference from definitions — args and flags are inferred automatically. No manual type annotations, no generics to wrangle. You define a flag as type: "string" and it flows through to your handler.
- Compile-time validation — catches flag alias collisions and variadic arg mistakes before your code runs, not at runtime.
- Zero runtime dependencies — @crustjs/core is ~3.6kB gzipped (21kB install). For comparison: yargs is 509kB, oclif is 411kB.
- Composable modules — core, plugins, prompts, styling, validation, and build tooling are all separate packages. Install only what you need.
- Plugin system — middleware-based with lifecycle hooks (preRun/postRun). Official plugins for help, version, and shell autocompletion.
- Built for Bun — no Node compatibility layers, no legacy baggage.
Quick example:
import { Crust } from "@crustjs/core";
import { helpPlugin, versionPlugin } from "@crustjs/plugins";
const main = new Crust("greet")
.args([{ name: "name", type: "string", default: "world" }])
.flags({ shout: { type: "boolean", short: "s" } })
.use(helpPlugin())
.use(versionPlugin("1.0.0"))
.run(({ args, flags }) => {
const msg = `Hello, ${args.name}!`;
console.log(flags.shout ? msg.toUpperCase() : msg);
});
await main.execute();
bun create crust my-cli
Happy to answer any questions about the design decisions or internals.