The craft CLI runs on Bun. Routecraft itself is also a library, so Node users embed it programmatically.

CLI runtime: Bun

The craft bin ships with a #!/usr/bin/env bun shebang. bunx craft, bun run start, and craft all execute under Bun natively. There is no Node fallback and no tsx bridge.

Version floor

Routecraft requires Bun 1.1.0 or later. The CLI checks process.versions.bun at startup and exits with a clear error message if Bun is missing or below the floor.

$ craft run index.ts
[routecraft] Bun 1.0.0 is not supported. Routecraft requires Bun 1.1.0 or
later. Upgrade Bun: https://bun.com/docs/installation.

If Bun is not installed at all, the OS resolves env bun and reports bun: command not found. The CLI cannot start without Bun.

Why Bun-only

Bun has native TypeScript support, which means the CLI can load .ts capability files directly with no tsc step and no tsx loader bridge. Bun also provides built-in drivers (Bun.sql, Bun.s3, bun:sqlite, native YAML and TOML parsers) that adapters can use without pulling in extra dependencies. Standardising on Bun for the CLI lets every adapter rely on those primitives and keeps the install footprint small.

Embedding in Node

Users who want to run Routecraft inside a Node application embed the library directly instead of going through the CLI. The library itself works on Node 22.6 or later (for runtime type stripping) and is recommended on Node 23.6 or later where stripping is on by default.

import { ContextBuilder, craft, direct, log } from "@routecraft/routecraft";

const route = craft()
  .id("greet")
  .from(direct<{ name: string }>())
  .transform((body) => `Hello, ${body.name}!`)
  .to(log());

const { context, client } = await new ContextBuilder().routes(route).build();
context.start();

await client.send("greet", { name: "World" });
await context.stop();

See Programmatic Invocation for the full embedding guide, including Express, Next.js, and Commander integrations.

Choosing a runtime

Related