burgee vs cac

burgee is not a drop-in for cac. There is no burgee/cac and burgee migrate does not rewrite a cac import. Compatibility lists a cac front end as planned and deferred: cac's downloads are almost entirely vite and vitest bundling it, not developers choosing it, so a façade would convert few people. Until one exists and is graded by cac's own tests, moving a cac CLI to burgee is a rewrite, and this page is here to help you decide whether it is worth one.

Is there a drop-in?

No. burgee's package.json exports front ends for commander (burgee/commander), yargs (burgee/yargs) and meow (burgee/meow), each graded by that host's own test suite. Nothing is exported for cac, so no cac program runs on burgee unchanged, and this page never calls burgee cac-compatible.

When cac is the better choice

cac is the lightest framework in the landscape, and burgee's own gates say it is lighter than burgee. Measured against cac@7.0.0, the version the benchmark suite resolves, with each ratio taken between the two in the same run:

• Bundle size. The lighter-than-cac gate — burgee lighter in a bundle than cac alone — is not met (2.316×): burgee's core bundles to 24,202 bytes and cac to 10,452.
• Cold start. cac starts faster in every run on record. Across the 178 runs committed under benchmarks/results/cli-benchmarks/, burgee's full-run cold start is 1.29×–2.13× cac's and never at or below 1. The 174 CI runs fall between 1.29× and 1.55×; the four higher figures are from a developer laptop. The latest CI run, 2026-09-24-866b972-ci.json (2026-09-24), measured 1.48×. The published target of at or below cac is recorded as not met.
• Installed size. 1304 KB for burgee against 40 KB for cac.

Those gaps are not scheduled to close. The README says why: cac's bytes are a parser and a help renderer, and burgee's are that plus coercion, choices, option relations, Standard Schema, config precedence, bounded shutdown, terminal restore and agent detection, so closing them would mean deleting the product. If your CLI needs none of that and every byte counts, choose cac.

When burgee is the better choice

• You would otherwise add the rest yourself. A cac program that wants its config file read, its shutdown bounded on every path out and its cursor handed back on Ctrl-C installs cosmiconfig, exit-hook and restore-cursor. Against that stack burgee's lighter-than-cac-at-parity gate is met (0.248×): 24,202 bytes against 97,711. Both gates are the README's, and every bundle figure on this page is rewritten from a fresh build by npm run readme:gates, so it cannot drift from what the build measures.
• You want an agent to drive it. The comparison marks cac without a --json envelope, an exit-code contract, --schema, --mcp or shell completions. burgee projects all five from one declaration; see Your CLI is an agent tool.
• You want plugins. The comparison marks cac without them; burgee's plugins are shared across programs.

Weight against cac

From burgee vs the alternatives, where both sides are measured by npm run bench in one run on one machine (2026-09-09), with downloads from the research snapshot of 2026-09-06. Milliseconds are a property of the machine that measured them; the ratios above are the figures that cancel it out:

cac wins every row, and every row stays on the page. The case for burgee is the capability list above, not weight.

Moving a command across

There is no import to swap, so each cli.command() chain becomes a defineCommand. The shapes are close: cac's <name> in the command string becomes an entry in arguments, each .option() becomes a key in options, and .action() becomes run. What is new is effects, which says what running the command does to the world, and which --mcp reads.

Before, with cac 7.0.0:

import cac from 'cac';

const cli = cac('hello');
cli
  .command('greet <name>', 'Greet someone')
  .option('--shout', 'uppercase it')
  .action((name, options) => {
    const line = `Hello, ${name}`;
    console.log(options.shout ? line.toUpperCase() : line);
  });
cli.help();
cli.parse();

After, with burgee:

import { defineCommand, defineProgram, run } from 'burgee';

const program = defineProgram({
  name: 'hello',
  commands: [
    defineCommand({
      name: 'greet',
      description: 'Greet someone',
      effects: 'read_only',
      arguments: [{ name: 'name', required: true }],
      options: { shout: { type: 'boolean', description: 'uppercase it' } },
      run: ({ positionals, options }) => {
        const line = `Hello, ${positionals[0]}`;
        return options.shout ? line.toUpperCase() : line;
      },
    }),
  ],
});

await run(program);

The handler returns its result instead of printing it, so greet ada --json answers {"ok":true,"data":"Hello, ada",…} and a missing name exits 2. Help needs no cli.help(): every burgee program has it.