Bun vs Deno vs Node.js: JavaScript Runtimes Compared
Basics3 minInnovialabs editorial team
In short
For most production projects Node.js is still the safest choice; Bun stands out for speed and built-in tooling, Deno for its security model and out-of-the-box TypeScript.
The short answer
All three runtimes execute JavaScript outside the browser, but they aim at different goals:
- Node.js is the industry standard. The largest ecosystem, the most documentation and battle-tested solutions.
- Bun bets on speed and "all in one": package manager, bundler, test runner and TypeScript execution in a single binary.
- Deno bets on security and modern standards: network and file access must be granted explicitly, TypeScript and a formatter are built in.
If in doubt, start with Node.js. Switch runtimes only for a concrete benefit you can measure.
Comparison by key criteria
| Criterion | Node.js | Bun | Deno |
|---|---|---|---|
| Engine | V8 | JavaScriptCore | V8 |
| npm compatibility | Full, it is the native environment | High, with occasional gaps | Good via npm: and package.json |
| TypeScript | Via tooling or newer built-in features | Runs it directly | Runs it directly |
| Built-in tooling | Test runner, watch mode | Package manager, bundler, tests | Formatter, linter, tests |
| Security model | Full access by default | Full access by default | Denied by default, permission flags |
| Production maturity | Highest | Growing | Growing |
Speed
Bun often wins synthetic benchmarks: fast process startup, fast package installs, a fast HTTP server. But in a real application the bottleneck is usually the database, the network and external APIs, not the runtime.
Rule of thumb: measure your own scenario. If 90% of request time is spent in SQL, changing the runtime will barely help.
Where Bun's speed is noticeable right away:
- installing dependencies in CI;
- running tests and scripts;
- cold starts of small services.
npm compatibility
This is the main practical question. Node.js is the reference: every npm package is built for it.
- Bun implements most Node.js APIs and reads
package.json, so many projects run unchanged. Issues usually come from packages with native modules and rarely used APIs. - Deno supports importing
npm:packages and working withpackage.json, but it was historically built around URL imports and web standards, so some Node ecosystem tools need extra configuration.
Before migrating, check your key dependencies: ORM, database driver, payment SDKs, image processing libraries.
Security
Deno denies access to the network, files and environment variables by default. Permissions are granted explicitly:
deno run --allow-net --allow-read=./data server.ts
This limits the damage if a dependency turns out to be malicious. In Node.js and Bun a script gets all the permissions of the process by default. Node.js has its own permission model, but it has to be enabled separately.
How to choose
- Enterprise backend, long-term support, large team: Node.js.
- New service, development speed and CI matter, simple dependencies: Bun is worth a try.
- Scripts, utilities, edge functions, isolation matters: Deno.
- Just faster installs: use Bun as a package manager and keep Node.js as the runtime.
Common mistakes
- Migrating for benchmarks. Numbers from someone else's tests are not a gain in your project.
- Not checking hosting. Not every platform and Docker image supports Bun and Deno equally well.
- Mixing runtimes without agreement. A developer runs Bun locally while production runs Node, and "works on my machine" bugs follow.