Migrate from Yarn

Yarn is a package manager, not a runtime, so most of what you are "migrating" is configuration rather than code. Both Yarn Classic and Yarn Berry describe a project with a standard package.json, and Deno reads that directly: it installs and resolves the same npm dependencies and runs your scripts. A typical Yarn project runs under Deno with no changes.

The one Yarn feature that needs a decision is Plug'n'Play, Yarn Berry's default install mode. Deno does not use PnP; it installs a real node_modules directory. That is covered below.

Run your project

Install dependencies and run your entrypoint:

›_

cd my-yarn-app
deno install
deno run main.js

deno install reads your existing package.json and resolves the same npm packages, like yarn install. It writes a node_modules directory and its own deno.lock.

On your first deno install, when there is no deno.lock yet, Deno seeds it from a Yarn Classic (v1) yarn.lock, carrying over the versions and integrity hashes you already had pinned. Yarn Berry (v2+) uses a different lockfile format that Deno does not seed from; in that case Deno resolves your package.json ranges fresh, so review deno.lock before committing it.

Scripts defined in package.json run with deno task, the equivalent of yarn run:

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deno task start

If you also switch from running your app on Node to running it on Deno, expect one immediate difference: Deno is sandboxed by default. The first time your program touches the network, file system, or environment, Deno prompts for permission. Grant everything up front with deno run -A main.js to match Node's behavior, then tighten the flags later. See Security and permissions.

Yarn to Deno cheatsheet

Dependencies

Yarn	Deno
`yarn install`	`deno install`
`yarn add <pkg>`	`deno add <pkg>`
`yarn add -D <pkg>`	`deno add -D <pkg>`
`yarn remove <pkg>`	`deno remove <pkg>`
`yarn up <pkg>`	`deno update`
`yarn outdated`	`deno outdated`
`yarn install --immutable`	`deno ci`
`yarn npm audit`	`deno audit`
`yarn why <pkg>`	`deno why <pkg>`

Run and execute

Yarn	Deno
`node file.js`	`deno file.js`
`yarn <script>`	`deno task <script>`
`yarn run <script>`	`deno task <script>`
`yarn dlx <pkg>`	`dx <pkg>`

Deno also ships a formatter and linter in the box, so deno fmt and deno lint replace Prettier and ESLint with no extra dependencies.

Workspaces

Yarn stores workspace globs in package.json under workspaces, and Deno reads that field directly. A monorepo like this runs as-is:

package.json

{
  "workspaces": ["packages/*"]
}

Members reference each other through the workspace: protocol in their package.json dependencies, exactly as they do under Yarn. There is nothing to convert. See Workspaces for how resolution works.

Plug'n'Play

Yarn Berry defaults to Plug'n'Play, which skips node_modules and resolves packages through a generated .pnp.cjs file. Deno does not implement PnP. When you run deno install, it writes a normal node_modules directory instead, so you do not need PnP at all under Deno.

In practice this means the PnP-specific files and settings stop applying once you move to Deno:

.pnp.cjs and .pnp.loader.mjs are no longer used. Deno resolves from node_modules.
.yarnrc.yml resolver settings (nodeLinker, pnpMode, plugins) configure Yarn specifically and do not carry over.
yarn patch has no built-in Deno equivalent. Vendor the dependency or keep the patch in a fork.

What to watch for

Lifecycle scripts do not run by default. If a dependency relies on an install or postinstall script (native addons, node-gyp builds), allow it per package with deno install --allow-scripts=npm:<pkg>, or manage approvals with deno approve-scripts. This is a security default, not a missing feature.

Keep going

Migrate from Node.js. If you are also moving the runtime, this covers CommonJS and ES module resolution and the Node built-ins Deno supports.
Migrate from npm and Migrate from pnpm. The same Deno commands, with notes on each tool's workspace format.
Dependency management. npm, JSR, and package.json workflows in detail.
Supply chain management. deno audit, lockfile discipline, and minimum dependency age.