I have used npm since 2014. It worked. Dependencies installed. Scripts ran. Life went on.

But npm has accumulated friction over the years. Slow installs. The node_modules black hole. Lock file conflicts that require arcane knowledge to resolve. I tolerated it because alternatives felt like trading one set of problems for another.

Then I tried Bun.

Fast moving lights representing speed and performance

Speed That Changes Behavior

Bun is fast. Not “20% faster” fast. More like “install completes before I can switch to another tab” fast.

# npm
npm install
# ... time passes ...
# ... more time ...
added 847 packages in 45s

# bun
bun install
# blink
847 packages installed (2.1s)

This speed difference changes behavior. I now install dependencies without hesitation. Fresh clones feel instant. CI pipelines that used to spend minutes on dependency installation now spend seconds.

The Runtime Bonus

Bun is not just a package manager. It is a JavaScript runtime. This means I can run TypeScript files directly:

bun run src/script.ts

No compilation step. No ts-node configuration. Just execution.

For scripts and tooling, this is liberating. Need a quick data transformation? Write it in TypeScript, run it with Bun. The feedback loop tightens.

Terminal window with code commands running

Compatibility Surprised Me

I expected compatibility issues. I found almost none.

Bun reads package.json and generates its own bun.lockb lockfile. It handles npm packages, installs from the npm registry, and respects workspaces. My existing projects migrated by running bun install once.

The main compatibility consideration is bun.lockb being a binary format. If team members use different package managers, you will have parallel lockfiles. We standardized on Bun team-wide to avoid this.

What I Gave Up

Transparency into the lockfile. The binary format means no more reading lockfile diffs to understand what changed. I miss this occasionally when debugging dependency issues.

The npm ecosystem of tooling and documentation is larger. When I hit edge cases, Stack Overflow answers are npm-focused. I adapt them for Bun, which usually works.

The Migration

For existing projects:

  1. Delete node_modules and package-lock.json
  2. Run bun install
  3. Update CI scripts to use Bun
  4. Commit bun.lockb

That is it. No package.json changes. No dependency updates required.

Verdict

Bun removes friction I had stopped noticing. The speed improvement alone justified the switch. The TypeScript runtime is a bonus that keeps paying dividends.

If you are starting a new project or willing to standardize your team on one tool, Bun is worth the experiment. The switching cost is low, and the daily quality-of-life improvement is real.