Deno vs Node.js vs Bun: Which JavaScript Runtime to Pick

The short answer: Node.js is the most mature and has the largest ecosystem. Deno offers built-in TypeScript, security by default, and full npm compatibility since version 2. Bun is the fastest for startup and installs, with a built-in bundler, test runner, and package manager. All three use JavaScript and TypeScript, but they differ in philosophy, performance, and tooling.

Choosing a JavaScript runtime used to be simple because there was only one real option. Now there are three production-ready runtimes competing for the same workloads. The differences matter for website performance, build times, and developer experience. Here is how Deno, Node.js, and Bun compare in 2026.

Performance

Performance is the most visible difference between the three runtimes. Bun consistently leads in startup time and package installation benchmarks. Deno 2 claims over 105,000 HTTP requests per second compared to roughly 48,700 for Node.js 18 in their own benchmarks (tested on EC2 m5.metal instances). Bun's numbers are often higher still, though benchmarks vary depending on the workload and who runs them.

For CPU-bound tasks like data processing or cryptography, the gap narrows because all three runtimes run optimized native code for those operations. The biggest real-world differences show up in cold starts (important for serverless), dependency installation, and simple HTTP serving.

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TypeScript Support

This is where the three runtimes have converged the most, but the details still differ.

Deno

Deno was built for TypeScript from day one. You run .ts files directly with deno run file.ts. There is no config, no build step, and no transpiler to install. Deno also includes a built-in type checker that you can run with deno check.

Bun

Bun also runs TypeScript files directly. It strips types at execution time using its own fast transpiler, similar to how esbuild or swc work. Type checking is not included. You still need tsc or another tool if you want compile-time type errors.

Node.js

Node.js 24 introduced type stripping, which removes TypeScript annotations before running the file. This works for most TypeScript syntax, but features like enum, namespace, and parameter decorators require the --experimental-transform-types flag. It is a step forward, but not yet on the same level as Deno or Bun for zero-config TypeScript.

Wondering how your current stack handles TypeScript and build performance? We can run a free check and show you exactly what to improve.

Security Model

Deno

Deno is secure by default. A program has no access to the file system, network, or environment variables unless you grant permission with explicit flags:

deno run --allow-read --allow-net server.ts

This applies even to imported npm packages. If a dependency tries to read your file system without permission, it fails. This is a meaningful defense against supply chain attacks.

Node.js

Node.js 24 introduced a permission model using the --permission flag (promoted from experimental). It works similarly to Deno's model, restricting file, network, and child process access. The key difference: it is opt-in. By default, Node.js grants full access to everything, which is how it has always worked.

Bun

Bun has no built-in permission or security model. All code runs with full access to the system. If security sandboxing matters to your project, Bun relies on OS-level isolation (containers, sandboxes) rather than runtime-level controls.

Built-in Tooling

One of the biggest differences in 2026 is how much each runtime ships out of the box.

Deno has the most complete built-in toolchain. Bun prioritizes speed across its tools. Node.js has been catching up by adding a test runner, type stripping, and a permission model, but still relies on external tools for bundling, formatting, and linting.

Ecosystem and Compatibility

Node.js has the largest ecosystem by far, with over 2 million packages on npm. Both Deno and Bun are designed to be compatible with that ecosystem.

Deno 2 reads package.json, understands node_modules, and supports the npm: import specifier. Most Node.js applications run on Deno without modification. Deno also has its own registry at jsr.io for Deno-native and cross-runtime packages.

Bun reads package.json and installs from npm. It aims for full Node.js API compatibility, though some edge cases (native addons, certain Node.js internals) may not work identically.

For SEO-critical websites and production applications, ecosystem compatibility means you are not locked into a single runtime. You can start with Node.js and move to Bun or Deno later without rewriting your dependencies.

When to Pick Each Runtime

• Node.js is the safest choice for existing projects and maximum ecosystem support
• Deno offers the most complete built-in toolchain and the strongest security model
• Bun is the fastest runtime for startup, installs, and HTTP throughput in benchmarks
• All three support TypeScript and npm packages in 2026
• Performance differences matter most in serverless and cold-start scenarios

The JavaScript runtime landscape has matured. There is no single "best" option. The right choice depends on whether you prioritize ecosystem size, security defaults, or raw speed. For most modern websites, any of the three will serve you well.