# @metamask/snaps-cli > A CLI for developing MetaMask Snaps Latest version **8.4.1** (published 2026-03-06) · ISC license · 0 weekly downloads ## Install ```sh npm install @metamask/snaps-cli pnpm add @metamask/snaps-cli yarn add @metamask/snaps-cli bun add @metamask/snaps-cli ``` Provides the command `mm-snap`. ## Health **Score 65/100 (B)** — status: stable. Positive: has types; esm support; no vulnerabilities; high maintenance score; high quality score. Warnings: low downloads. ## Facts | | | |---|---| | Version | 8.4.1 | | Published | 2026-03-06 | | First published | 2021-09-09 | | Weekly downloads | 0 | | License | ISC | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Node | ^20 \|\| >=22 | | Dependencies | 43 | | Unpacked size | 775 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 858 | | Maintainers | danfinlay, kumavis, metamaskbot, gudahtt | | Keywords | MetaMask, Snaps, Ethereum | ## Links - npm: https://www.npmjs.com/package/@metamask/snaps-cli - Repository: https://github.com/MetaMask/snaps - Homepage: https://github.com/MetaMask/snaps/tree/main/packages/snaps-cli#readme - Issues: https://github.com/MetaMask/snaps/issues - npm.io page: https://npm.io/package/@metamask/snaps-cli ## Dependencies (43) - [ora](https://npm.io/package/ora.md) ^5.4.1 - [url](https://npm.io/package/url.md) ^0.11.1 - [util](https://npm.io/package/util.md) ^0.12.5 - [chalk](https://npm.io/package/chalk.md) ^4.1.2 - [yargs](https://npm.io/package/yargs.md) ^17.7.1 - [assert](https://npm.io/package/assert.md) ^2.0.0 - [buffer](https://npm.io/package/buffer.md) ^6.0.3 - [events](https://npm.io/package/events.md) ^3.3.0 - [semver](https://npm.io/package/semver.md) ^7.5.4 - [express](https://npm.io/package/express.md) ^5.1.0 - [process](https://npm.io/package/process.md) ^0.11.10 - [webpack](https://npm.io/package/webpack.md) ^5.97.1 - [punycode](https://npm.io/package/punycode.md) ^2.3.0 - [@swc/core](https://npm.io/package/@swc/core.md) 1.11.31 - [strip-ansi](https://npm.io/package/strip-ansi.md) ^6.0.1 - [swc-loader](https://npm.io/package/swc-loader.md) ^0.2.6 - [stream-http](https://npm.io/package/stream-http.md) ^3.2.0 - [os-browserify](https://npm.io/package/os-browserify.md) ^0.3.0 - [vm-browserify](https://npm.io/package/vm-browserify.md) ^1.1.2 - [webpack-merge](https://npm.io/package/webpack-merge.md) ^5.9.0 - [domain-browser](https://npm.io/package/domain-browser.md) ^4.22.0 - [string_decoder](https://npm.io/package/string_decoder.md) ^1.3.0 - [tty-browserify](https://npm.io/package/tty-browserify.md) ^0.0.1 - [@metamask/utils](https://npm.io/package/@metamask/utils.md) ^11.10.0 - [browserify-zlib](https://npm.io/package/browserify-zlib.md) ^0.2.0 - [path-browserify](https://npm.io/package/path-browserify.md) ^1.0.1 - [querystring-es3](https://npm.io/package/querystring-es3.md) ^0.2.1 - [readable-stream](https://npm.io/package/readable-stream.md) ^3.6.2 - [https-browserify](https://npm.io/package/https-browserify.md) ^1.0.0 - [crypto-browserify](https://npm.io/package/crypto-browserify.md) ^3.12.0 - [stream-browserify](https://npm.io/package/stream-browserify.md) ^3.0.0 - [timers-browserify](https://npm.io/package/timers-browserify.md) ^2.0.12 - [console-browserify](https://npm.io/package/console-browserify.md) ^1.2.0 - [@metamask/snaps-sdk](https://npm.io/package/@metamask/snaps-sdk.md) ^10.4.0 - [constants-browserify](https://npm.io/package/constants-browserify.md) ^1.0.0 - [@metamask/snaps-utils](https://npm.io/package/@metamask/snaps-utils.md) ^12.1.0 - [@metamask/superstruct](https://npm.io/package/@metamask/superstruct.md) ^3.2.1 - [terser-webpack-plugin](https://npm.io/package/terser-webpack-plugin.md) ^5.3.9 - [@metamask/snaps-sandbox](https://npm.io/package/@metamask/snaps-sandbox.md) ^1.0.1 - [webpack-bundle-analyzer](https://npm.io/package/webpack-bundle-analyzer.md) ^4.10.2 - [@metamask/snaps-rpc-methods](https://npm.io/package/@metamask/snaps-rpc-methods.md) ^14.3.0 - [@metamask/snaps-webpack-plugin](https://npm.io/package/@metamask/snaps-webpack-plugin.md) ^5.1.2 - [fork-ts-checker-webpack-plugin](https://npm.io/package/fork-ts-checker-webpack-plugin.md) ^9.0.2 ## Recent versions - 8.4.1 (latest) — 2026-03-06 - 0.38.4-flask.1 (flask) — 2023-09-20 - 1.0.0-prerelease.1 (next) — 2023-06-23 - 0.32.2 (dev) — 2023-03-30 - 8.4.0 — 2026-01-22 - 8.3.0 — 2025-08-20 - 8.2.0 — 2025-08-06 - 8.1.1 — 2025-07-09 - 8.1.0 — 2025-06-27 - 8.0.0 — 2025-06-10 - 7.2.0 — 2025-05-27 - 7.1.0 — 2025-04-23 - 7.0.0 — 2025-04-16 - 6.7.0 — 2025-02-11 - 6.6.1 — 2025-01-14 - … 107 more at https://npm.io/package/@metamask/snaps-cli/versions ## README # @metamask/snaps-cli A CLI for developing MetaMask Snaps. ## Installation Use Node.js `18.16.0` or later. We recommend [nvm](https://github.com/nvm-sh/nvm) for managing Node.js versions. Install a dev dependency in your snap project using `yarn` or `npm`: - `npm install --save-dev @metamask/snaps-cli` - `yarn add -D @metamask/snaps-cli` ## Usage ```text Usage: mm-snap [options] Commands: mm-snap build Build snap from source [aliases: b] mm-snap eval Attempt to evaluate snap bundle in SES [aliases: e] mm-snap manifest Validate the snap.manifest.json file [aliases: m] mm-snap sandbox Start a sandbox server to interact with the Snap mm-snap serve Locally serve Snap file(s) for testing [aliases: s] mm-snap watch Build Snap on change [aliases: w] Options: --version Show version number [boolean] -c, --config Path to config file [string] -h, --help Show help [boolean] Examples: mm-snap build Build './src/index.js' as './dist/bu ndle.js' mm-snap build --config ./snap.config.bui Build './src/index.js' as './dist/bu ld.ts ndle.js' using the config in './snap .config.build.ts' mm-snap manifest --fix Check the snap manifest, and fix any errors mm-snap watch --port 8000 The snap input file for changes, and serve it on port 8000 mm-snap serve --port 8000 Serve the snap bundle on port 8000 ``` ## MetaMask Snaps MetaMask Snaps enables trustlessly extending the functionality of MetaMask at runtime. A snap consist of two things: a JSON manifest and a JavaScript bundle. At present, snaps can be published as npm packages on the public npm registry, or hosted locally during development. In the future, it will be possible to publish snaps on many different platforms, including arbitrary npm registries and IPFS. We recommend building your snap using this tool. You can bundle your snap using your own tools, but it must run in SES and only use the global APIs that MetaMask exposes at runtime. Although snaps currently execute in the browser, some browser APIs are not available to snaps, and snaps do not have DOM access. ### The Snap Manifest Your manifest must be named `snap.manifest.json` and located in the root directory of your npm package. Here's an example manifest: ```json { "version": "0.7.0", "proposedName": "Dialog Example", "description": "A MetaMask Snap template.", "repository": { "type": "git", "url": "https://github.com/MetaMask/template-snap.git" }, "source": { "shasum": "w3FltkDjKQZiPwM+AThnmypt0OFF7hj4ycg/kxxv+nU=", "location": { "npm": { "filePath": "dist/bundle.js", "iconPath": "images/icon.svg", "packageName": "@metamask/template-snap", "registry": "https://registry.npmjs.org/" } } }, "initialPermissions": { "snap_dialog": {}, "endowment:rpc": { "dapps": true, "snaps": false } }, "manifestVersion": "0.1" } ``` Refer to [the Snaps publishing specification](https://github.com/MetaMask/specifications/blob/main/snaps/publishing.md) for more information about the manifest. > **Note**: If your snap is not compatible with the publishing specification, > your snap may not work properly or install at all. ### Assumed Project Structure This tool has default arguments assuming the following project structure: ```text snap-project/ ├─ package.json ├─ src/ │ ├─ index.js ├─ snap.manifest.json ├─ dist/ │ ├─ bundle.js ├─ ... (all other project files and folders) ``` Source files other than `index.js` are located through its imports. The defaults can be overwritten using the `snap.config.js` or (`snap.config.ts`) [config file](#configuration). ## Configuration The MetaMask Snaps CLI supports a configuration file. It can be either: - `snap.config.js` - a CommonJS module. - `snap.config.ts` - a TypeScript module. The file should be placed in the project root directory. ### Example #### JavaScript ```javascript module.exports = { input: 'src/index.js', output: { path: 'dist', }, server: { port: 9000, }, }; ``` #### TypeScript The CLI has full support for TypeScript out of the box. `@metamask/snaps-cli` exports a `SnapConfig` type that can be used to type the configuration object. ```typescript import type { SnapConfig } from '@metamask/snaps-cli'; const config: SnapConfig = { input: 'src/index.js', output: { path: 'dist', }, server: { port: 9000, }, }; export default config; ``` The configuration file should not be published. ### Options - [`input`](#input) - [`output`](#output) - [`output.path`](#outputpath) - [`output.filename`](#outputfilename) - [`output.clean`](#outputclean) - [`output.minimize`](#outputminimize) - [`server`](#server) - [`server.enabled`](#serverenabled) - [`server.root`](#serverroot) - [`server.port`](#serverport) - [`environment`](#environment) - [`stats`](#stats) - [`stats.verbose`](#statsverbose) - [`stats.builtIns`](#statsbuiltins) - [`stats.buffer`](#statsbuffer) - [`customizeWebpackConfig`](#customizewebpackconfig) - [`experimental`](#experimental) - [`experimental.wasm`](#experimentalwasm) #### `input` - Type: `string` - Default: `"src/index.js"` The entry point of your snap. This is the file that will be bundled. #### `output` - Type: `object` The output configuration. ##### `output.path` - Type: `string` - Default: `"dist"` The output directory. ##### `output.filename` - Type: `string` - Default: `"bundle.js"` The output filename. ##### `output.clean` - Type: `boolean` - Default: `false` Whether to clean the output directory before building. ##### `output.minimize` - Type: `boolean` - Default: `true` Whether to minimize the bundle. This will remove comments and whitespace from the bundle, mangle variable names, and perform other optimizations. #### `sourceMap` - Type: `boolean | "inline"` - Default: `true` Whether to generate a source map. If `"inline"`, the source map will be inlined in the bundle. Otherwise, it will be written to a separate file. #### `evaluate` - Type: `boolean` Whether to evaluate the bundle. This will check the bundle for compatibility issues with the MetaMask Snaps runtime. If there are any issues, the CLI will exit with an error. #### `manifest` - Type: `object` The snap manifest configuration. ##### `manifest.path` - Type: `string` - Default: `"snap.manifest.json"` The path to the snap manifest, i.e., `snap.manifest.json`. ##### `manifest.update` - Type: `boolean` - Default: `true` Whether to update the manifest with the bundle shasum, and any other possible updates. If `false`, the manifest will not be updated, and an error will be thrown if the manifest is not up-to-date. #### `server` - Type: `object` The development server configuration. The development server is used to test your snap during development, using the `watch` and `serve` commands. ##### `server.enabled` - Type: `boolean` - Default: `true` Whether to enable the development server. If `false`, the development server will not be started when running the `watch` command. This option has no effect on the `serve` command. ##### `server.root` - Type: `string` - Default: `process.cwd()` The root directory of the development server. This is the directory that will be served by the development server. ##### `server.port` - Type: `number` - Default: `8081` The port to run the development server on. If set to `0`, a random port will be used. #### `environment` - Type: `Record` The environment configuration. This is used to set environment variables for the snap, which can be accessed using `process.env`. In addition to the environment variables set by the user, the following environment variables are set by the CLI: - `NODE_ENV` - `"production"`. - `NODE_DEBUG` - `false`. - `DEBUG` - `false`. #### `stats` - Type: `object` The stats configuration, which controls the log output of the CLI. ##### `stats.verbose` - Type: `boolean` - Default: `false` Whether to enable verbose logging. If `true`, the CLI will log more information. ##### `stats.builtIns` - Type: `false | object` - Default: `{ ignore: [] }` Whether to check for missing built-in modules. The MetaMask Snaps CLI does not support Node.js built-ins out of the box, and any used built-ins must be provided through the `customizeWebpackConfig` option. When enabled, the CLI shows a warning if a built-in module is used, but not provided. ###### `stats.builtIns.ignore` - Type: `string[]` A list of built-in modules to ignore. This is useful if the built-in module is not actually used in the snap, but is added by a dependency. ###### `stats.buffer` - Type: `boolean` - Default: `true` Whether to show a warning if `Buffer` is used, but not provided. The `Buffer` global is not available in the MetaMask Snaps runtime by default, and must be provided through the `customizeWebpackConfig` option. #### `customizeWebpackConfig` - Type: `(config: webpack.Configuration) => webpack.Configuration` A function that can be used to customize the Webpack configuration. This is useful if you need to add a Webpack plugin, provide a polyfill, add a loader, and so on. The function receives the Webpack configuration object, and should return the modified configuration object. For convenience, `@metamask/snaps-cli` exports a `merge` function (re-exported from `webpack-merge`) that can be used to merge the configuration object with the default configuration. The default configuration can be found in [`src/webpack/config.ts`](./src/webpack/config.ts). ```typescript import type { SnapConfig } from '@metamask/snaps-cli'; import { merge } from '@metamask/snaps-cli'; const config: SnapConfig = { customizeWebpackConfig: (config) => merge(config, { plugins: [ // Add a plugin. ], module: { rules: [ // Add a loader. ], }, }), }; export default config; ``` #### `experimental` - Type: `object` Experimental features. These features are not stable, and may change in the future. ##### `experimental.wasm` - Type: `boolean` Whether to enable WebAssembly support. When this is enabled, WebAssembly files can be imported in the snap, for example: ```typescript import program from './program.wasm'; // Program is initialised synchronously. // ... ``` --- _Source: https://npm.io/package/@metamask/snaps-cli · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._