bun add: install a package with Bun (dev, exact, global)

bun add express adds a package to the dependencies of package.json, installs it into node_modules and updates the bun.lock lockfile, the Bun equivalent of npm install express. Add -d (--dev) for devDependencies, --exact to save the version without a caret, and -g to install a command-line tool globally.

Add a dependency and a dev dependency

export NO_COLOR=1
echo '{ "name": "app", "private": true }' > package.json
npx --yes bun@1 add is-odd@3.0.1 2>&1 | grep -E "^installed"
npx --yes bun@1 add -d --exact is-number@7.0.0 2>&1 | grep -E "^installed"
cat package.json
ls bun.lock node_modules/is-odd/package.json

installed is-odd@3.0.1
installed is-number@7.0.0
{
  "name": "app",
  "private": true,
  "dependencies": {
    "is-odd": "3.0.1"
  },
  "devDependencies": {
    "is-number": "7.0.0"
  }
}
bun.lock
node_modules/is-odd/package.json

Bun prints one installed line per package you asked for, writes bun.lock (a text lockfile; Bun 1.1 and older wrote the binary bun.lockb) and creates node_modules. The example starts Bun through npx bun@1 so it needs only Node.js; with Bun installed the commands are bun add is-odd@3.0.1 and bun add -d --exact is-number@7.0.0.

Variants

Defaults and pitfalls

• Ranges. Without a version, Bun saves a caret range like npm does; an exact version you type (is-odd@3.0.1) is saved as written, as the example shows. Set exact = true under [install] in bunfig.toml to save exact versions by default.
• Lifecycle scripts. Dependencies' postinstall scripts are not run unless the package is listed in trustedDependencies; packages that build native code may look installed but not work until you trust them.
• Version not found. A version or tag that does not exist fails with No version matching found for specifier; check the published versions with bun info pkg or npm view pkg versions.
• CI. Use bun install --frozen-lockfile in CI, not bun add. It fails with lockfile had changes, but lockfile is frozen when package.json and bun.lock disagree.
• Workspaces. In a monorepo, run bun add inside the package folder, or use --filter, to add the dependency to that package rather than to the root.

How to confirm it worked

cat package.json shows the new entry in the right section, bun pm ls lists the installed top-level packages with their versions, and ls node_modules/PACKAGE shows that it is on disk. Running bun install again without changes should report that nothing needs to be installed.

FAQ