# bun dedupe

> Remove duplicate versions of packages from bun.lock

Over time, `bun.lock` can accumulate several versions of the same package even though one of them satisfies every range. For example, it can contain both `esbuild@0.15.10` and `esbuild@0.15.11` when the ranges are `^0.15.7` and `^0.15.8`. `bun dedupe` collapses these onto the smallest set of already-locked versions (preferring newer ones), saves `bun.lock`, and installs.

```bash terminal icon="terminal"
bun dedupe
```

```
bun dedupe v1.4.0 (abc12345)

↳ esbuild 0.15.10 → 0.15.11
↳ react 18.2.0 → 18.3.1

2 duplicate versions removed, 3 packages installed (checked 5 packages) [12.00ms]
```

Each row is a version Bun removed and the version its dependents now use.

`bun dedupe` only chooses between versions already in the lockfile and never modifies `package.json`. It never fetches new versions from the registry and never moves a dependency outside its range. Use [`bun update`](/pm/cli/update) for that.

### `--check` and `--dry-run`

`--check` reports what Bun would remove without changing anything, and exits `1` if there are duplicates. Use it in CI:

```bash terminal icon="terminal"
bun dedupe --check
```

```
bun dedupe v1.4.0 (abc12345)

↳ esbuild 0.15.10 → 0.15.11
↳ react 18.2.0 → 18.3.1

2 duplicate versions can be removed (checked 5 packages) [9.00ms]
  bun dedupe
```

`--dry-run` prints the same output but always exits `0`.

`--lockfile-only` rewrites `bun.lock` without installing.

### Notes

- Bun respects overrides and catalogs. It re-points each dependency using its effective range.
- Bun may move a direct dependency to an _older_ locked version if that's the only way to remove a duplicate (e.g. a transitive dependency pins it exactly). Use `bun update` or an [override](/pm/overrides) if you want the newer one to win.
- Bun never removes versions in `patchedDependencies`. If that forces another version to be kept too, Bun prints a `kept …` line explaining why.
- Dependencies on a dist-tag, git URL, or tarball keep their resolved version.
- Requires a lockfile that matches `package.json`. If dependencies changed since the last install, it exits with `bun.lock does not match package.json`. Run `bun install` first. Bun migrates a `package-lock.json`, `yarn.lock`, or `pnpm-lock.yaml` automatically.
- Cannot be combined with `--frozen-lockfile`, `--production`, or `--no-save`; use `--check` instead.
- With the isolated linker, several copies of the _same_ version that differ only in peer dependencies are not duplicates, and Bun does not report them. [`bun prune`](/pm/cli/prune) cleans up stale store entries.