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Alex Aslam
Alex Aslam

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Bun vs. Deno vs. Node.js: The Ultimate JavaScript Runtime Showdown

#webdev #beginners #javascript #programming

The Great JavaScript Runtime Debate

When we rebuilt our analytics platform last year, we faced a critical decision:

Should we stick with Node.js, bet on Deno, or go all-in on Bun?

After 6 months of testing, migrating, and debugging, here’s what we learned—and which runtime won our stack.

1. The Contenders

🥇 Node.js: The Veteran

✔ Mature ecosystem (1.3M+ packages)
✔ Proven at scale (Netflix, PayPal, LinkedIn)
✔ Full observability (APM, logging, profiling)

🚀 Deno: The Secure Upstart

✔ Built-in TypeScript (no config needed)
✔ Security by default (explicit permissions)
✔ Modern tooling (deno compile, deno test)

⚡ Bun: The Speed Demon

✔ Blazing fast (3x quicker than Node in benchmarks)
✔ All-in-one toolkit (bundler, test runner, package manager)
✔ Node.js compatibility (most apps work out of the box)

2. Benchmark Battles

Test Node.js Deno Bun
Cold start (ms) 120 85 32
npm install time 12s N/A 0.4s
HTTP req/sec 8,000 9,200 28,000
Memory usage (MB) 210 180 95

Tests on AWS EC2 t3.xlarge, Node 20, Deno 1.37, Bun 1.0

3. Real-World Tradeoffs

🔧 Developer Experience

  • Bun won (zero-config testing, built-in bundler)
  • Deno frustrated us (limited VS Code debugging)
  • Node.js felt outdated (node_modules bloat)

🛡️ Security

  • Deno won (explicit file/network permissions)
  • Bun was surprisingly good (limited attack surface)
  • Node.js required extra hardening

📦 Ecosystem

  • Node.js won (every package just works)
  • Bun was 90% compatible (bcrypt failed)
  • Deno struggled (many npm packages needed patches)

4. The Verdict

🏆 Winner: Bun (for our use case)

  • Why? Raw speed + dev experience outweighed ecosystem gaps.
  • Compromise: We still use Node.js for some legacy microservices.

🥈 Runner-Up: Node.js

  • When we use it: Projects needing sharp, prisma, or Kubernetes maturity.

🥉 Honorable Mention: Deno

  • Best for: Internal tools where security matters most.

5. Migration Tips

✔ Start small (try Bun on a non-critical service first)
✔ Profile before switching (Bun’s speed varies by workload)
✔ Keep Node.js as a fallback (for problematic dependencies)

Key Takeaways

🔹 Bun is fastest, but not perfect (watch for native module issues).
🔹 Node.js still dominates for complex, large-scale apps.
🔹 Deno shines for security-first projects.

Which runtime are you betting on? Have you tried migrating?

Further Reading

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