Yarn

Yarn is an open-source JavaScript package manager and project manager. Originally created at Facebook in 2016, Yarn is now a fully independent community-governed project. The current generation — Yarn Berry, currently v4 — lives at yarnpkg/berry and is written in TypeScript under the BSD-2-Clause license.

Yarn was the first package manager designed specifically around workspaces and introduced Plug'n'Play (a node_modules-free module resolution strategy), Zero-Installs (committable caches for instant clones), Constraints (a cross-workspace policy DSL), a rich protocol system, and a first-class plugin API.

This repository is the API Evangelist catalog entry for Yarn. It captures the Yarn surface area in apis.yml along with supporting artifacts.

Surfaces Profiled

• Yarn CLI — yarn install, add, remove, up, run, exec, dlx, info, why, pack, rebuild, dedupe, node, bin, search, upgrade-interactive, stage
• Yarn Workspaces — yarn workspace, yarn workspaces foreach, yarn workspaces focus, yarn workspaces list
• Yarn Plug'n'Play (PnP) — node_modules-free dependency resolution via a single .pnp.cjs manifest, plus a Rust implementation (pnp-rs)
• Yarn Zero-Installs — commit the cache so clones bootstrap with no yarn install
• Yarn Constraints — JavaScript and Prolog DSL for cross-workspace policy enforcement
• Yarn Protocols — npm:, git:, github:, file:, link:, portal:, patch:, exec:, workspace:, and http(s):
• Yarn Plugin API — register commands, resolvers, fetchers, linkers, and lifecycle hooks via @yarnpkg/core
• Yarn Version (Release Workflow) — deferred per-workspace version decisions applied at release time
• Yarn Patch — yarn patch / yarn patch-commit for first-class dependency patching
• Yarn DLX — ephemeral package execution (Yarn's npx replacement)

Key Properties

• License: BSD-2-Clause
• Governance: independent community project, GOVERNANCE.md in yarnpkg/berry
• Language: TypeScript (~85%), with Rust for pnp-rs
• Distribution: Corepack (recommended), or npm install -g yarn
• Pin to project: the packageManager field in package.json, or yarn set version stable
• Configuration: .yarnrc.yml
• Manifest: package.json
• Lockfile: yarn.lock (text-based, deterministic)

Ecosystem Packages

Package	Purpose
@yarnpkg/core	Programmatic API used by the CLI and plugins
@yarnpkg/cli	Command-line interface built on @yarnpkg/core
@yarnpkg/pnp	Plug'n'Play hook generation
@yarnpkg/fslib	Type-safe filesystem abstraction
@yarnpkg/shell	Portable bash-like shell interpreter for package.json scripts
@yarnpkg/sdks	Editor SDKs (VS Code, Vim, etc.) for PnP integration

Default Plugins (selected)

• plugin-npm — npm registry resolution
• plugin-pnp — Plug'n'Play installation
• plugin-workspace-tools — monorepo coordination
• plugin-npm-cli — yarn npm publish / login / audit / tag / whoami
• plugin-constraints — yarn constraints enforcement
• plugin-typescript — automatic @types/* co-installation
• plugin-interactive-tools — yarn upgrade-interactive, yarn search
• plugin-stage — stage Yarn files to version control

Artifacts

• apis.yml — APIs.json v0.16 catalog entry
• vocabulary/yarn-pkg-vocabulary.yml — Yarn vocabulary
• json-ld/yarn-pkg-context.jsonld — JSON-LD context for Yarn concepts
• json-schema/yarn-pkg-workspace-schema.json — JSON Schema for a Yarn workspace package.json

References

• Homepage: https://yarnpkg.com
• Getting started: https://yarnpkg.com/getting-started
• Install: https://yarnpkg.com/getting-started/install
• CLI reference: https://yarnpkg.com/cli
• Programmatic API: https://yarnpkg.com/api
• Migration guide: https://yarnpkg.com/migration/guide
• GitHub: https://github.com/yarnpkg/berry
• RFCs: https://github.com/yarnpkg/rfcs
• Discord: https://discord.gg/yarnpkg
• Open Collective: https://opencollective.com/yarnpkg

License

This catalog entry's content is published under the API Evangelist editorial license. Yarn itself is licensed under BSD-2-Clause.