Bun vs Deno: which runtime wins the 2026 Node.js migration wave

Speed and cold starts

Bun 1.3.11 processes 52,000 synthetic HTTP requests per second. Node.js 24 manages 13,000. Deno 2.6 handles 29,000. The Strapi report from June 2026 shows that Bun manages 52,000 requests per second whereas Node.js manages only 13,000, yet this gap collapses to 12,400 versus 12,000 once database operations and JSON serialization enter the request path. Bun achieves 8 to 15 millisecond cold starts. Node.js takes 60 to 120 milliseconds. Deno users experience 40 to 60 millisecond cold starts. In AWS Lambda, Bun cold-starts in 290 ms compared to 940 ms for Node.js. This 290 millisecond cold start provides a 69 percent reduction compared to Node.js 940 millisecond latency. Bun relies on Apple’s JavaScriptCore engine and the Zig programming language. Node.js and Deno use Google’s V8 engine. V8 excels in computational workloads, helping Node.js achieve 4,200 operations per second in React Server-Side Rendering tests. Bun’s JavaScriptCore engine uses a tiered compilation strategy involving LLInt, Baseline JIT, DFG, and FTL to prioritize startup speed and initial execution throughput. Bun.serve() implements routing natively in Zig and uses JavaScriptCore’s fast-path for short-lived handler functions. In a synthetic HTTP test, Bun 1.2 achieved 245,000 requests per second compared to Node 22’s 68,000 requests per second. The Bun 1.3.11 release provides a zero-config frontend dev server with hot reloading. Bun wins for speed.

Ecosystem and compatibility

Bun 1.3.11 provides 99.4% compatibility with the top 1,000 npm packages. Node.js supports 100% of the 2.1 million npm packages. In a dramatic comparison, Bun 1.3.11 installs dependencies in 1 second, while npm 11 takes 20 seconds. Bun uses 165,000 system calls for installations, whereas npm 11 requires nearly 1 million system calls. Bun’s installer reached 12 million weekly downloads by May 2026. Bun holds 87,600 GitHub stars. Node.js has 109,000 GitHub stars, and Deno possesses 106,000 stars. Anthropic acquired Bun in December 2025. Node.js maintains 30-month LTS cycles for enterprise reliability. Node.js distribution infrastructure logged 4.61 billion downloads in the first seven months of 2026. Bun 1.2 added Postgres support via Bun.SQL in January 2025. Bun 1.3 added a text-based lockfile in October 2025. Bun provides support for package.json workspaces compatible with the existing npm/Yarn workspace convention. Bun’s package manager is 35x faster than npm in a large monorepo with 1,847 dependencies. Node.js 24 includes the URLPattern API and WebAssembly Memory64. You should check your specific native addons before migrating. Bun lacks a formal LTS policy. Node dominates enterprise.

Will the migration risk outweigh the performance gains?

Security and toolchains

Deno 2.6 uses a permission model with zero permissions by default. Developers use flags like –allow-read or –allow-net. Bun has no filesystem permission or sandboxing system. Deno processes TypeScript in 38 ms. Node.js 24 supports experimental type stripping via the –experimental-strip-types flag. Bun bundles a runtime, package manager, bundler, and test runner in a single binary. Deno includes a formatter, linter, and test runner. Node.js includes a built-in test runner. Deno includes Deno KV for globally consistent key-value storage. Node.js uses the Undici 7 HTTP client. Deno 2.0 introduced full package.json compatibility. Deno 2.6 added –ignore-read and –ignore-env flags to fine-tune access. Deno 2.6 uses the built-in deno audit tool to scan dependencies against the GitHub CVE database. Deno’s native TypeScript support allows developers to execute .ts and .tsx files directly without external transpilers. Bun handles full TypeScript syntax, including enums, decorators, and namespaces. Bun’s Jest-compatible test runner uses the same API as Jest, including describe, it, and expect. Deno 2.6 employs a permission model that requires explicit approval for scripts to access files, networks, or environment variables. Deno includes a built-in key-value store that works locally with SQLite and in production with a distributed system. Deno focuses on security.