npm vs Yarn
npm vs Yarn: install speed, lockfile behavior, and whether switching package managers is worth the churn today.
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The short answer
Modern npm (v7+) has closed most of the gap that made Yarn's early speed and determinism advantages compelling, so for most projects sticking with whichever one is already in your lockfile beats migrating. Yarn (via Berry/PnP) still pulls ahead for very large monorepos where install speed and strict dependency resolution matter enough to justify the tooling change.
| Dimension | npm | Yarn |
|---|---|---|
| Comes with Node | Yes, bundled by default | No, separate install |
| Lockfile | package-lock.json | yarn.lock |
| Workspaces/monorepo | Supported since npm 7 | Mature, plus Plug'n'Play mode |
| Install speed | Improved a lot, still slower at huge scale | Fast, especially with PnP/caching |
| Determinism | Lockfile-based, solid since v7 | Lockfile-based; PnP skips node_modules entirely |
Choose npm when
- →You want zero extra setup — npm ships with Node, so there's nothing new to install or for contributors to learn.
- →You're on a small-to-medium project where the historical performance gap with Yarn doesn't actually show up.
- →You want the tool most tutorials, CI templates, and existing answers already assume.
Choose Yarn when
- →You're managing a large monorepo where install time and strict, reproducible dependency resolution genuinely matter.
- →You want Plug'n'Play mode's option to skip node_modules entirely, which can meaningfully speed up CI.
- →Your team already has Yarn-specific tooling or workflows (workspaces, constraints) built around it.
The catch nobody mentions
The gap that once decided this argument — npm having no lockfile at all before v5 — closed years ago, and most 'Yarn is faster and safer' claims online are stale. Switching an existing project's package manager mid-stream is real work (regenerating lockfiles, retraining CI, occasional resolution differences that surface subtly broken behavior), so don't switch without a specific problem the switch would actually fix.
Questions
Is Yarn still meaningfully faster?
Not in the way it was in 2016. npm added a lockfile and a cache and closed most of the gap, so the honest answer for a typical project is that the difference no longer justifies switching on speed alone.
Can I use both in one project?
No. Two lockfiles disagree about resolved versions, so what you install depends on which command someone ran. Pick one, commit its lockfile, and delete the other.
What does Yarn offer that npm does not?
Plug'n'Play, which skips node_modules entirely and resolves from a single archive, plus more mature workspace tooling. Both are real advantages for large monorepos and largely irrelevant for a single package.
Which should CI use?
The lockfile-respecting command for whichever you chose — npm ci or yarn install --immutable. Both fail if the lockfile and manifest disagree, which is exactly what you want a build to do rather than silently resolving something new.
What about pnpm?
It links packages from a shared content-addressed store rather than copying them, which saves substantial disk space and installs quickly. It also enforces stricter dependency rules, which surfaces packages relying on something they never declared.
How risky is switching?
Low for a small project and worth planning for a large one, because resolution differences can surface a version you were not previously getting. Regenerate the lockfile deliberately and run the full test suite rather than assuming parity.