Is Nub a Viable Alternative to Bun? An In‑Depth Look

Two months after Bun 1.4 (v1.4) announced a 66.8% Node.js compatibility rate, its creator Colin McDonnell posted a comparison chart showing Nub at 98.6% compatibility. The author revisits Nub (v0.8.1) to verify what the numbers represent.

Zod Author’s Node.js Toolbox

Colin McDonnell, known for creating Zod and contributing to early tRPC, previously worked on Bun and EdgeDB. His background explains Nub’s focus: rather than building a new JavaScript engine, he improves the Node.js development experience.

Nub defines itself as an "integrated toolkit based on Node.js". Its core is a Rust CLI that ultimately hands execution to the official Node binary.

The execution flow can be summarized as: nub index.ts – Nub selects an appropriate Node version, loads hooks, polyfills, and experimental flags, then launches the real Node process.

In a small verification on Node v22.23.1, a TypeScript file containing an enum (unsupported by native Node type erasure) runs successfully with Nub v0.8.1, printing { status: 'ready', node: 'v22.23.1', runtime: 'node' }. Disabling Nub’s enhancements with --node reproduces the ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX error, confirming that Nub merely augments Node rather than replacing it.

How the 98.6% Figure Was Obtained

Colin’s August 22 chart used Node v25.8.1 and a test suite of 4 366 items, with Nub passing 4 306 (98.6%) and Bun v1.4 passing 2 915 (66.8%). A few days later the suite was upgraded to Node v26.7.0, expanding to 5 046 items; the latest results show Nub 98.5%, Deno 74.2%, Bun 68.1%.

The test methodology mirrors Node’s own compatibility tests and Deno’s test scope, running the same files across Node, Nub, Bun, and Deno. Under the denoExclusions filter, Nub passes 4 968 of 5 046 items, Bun 3 438, and Deno 3 742.

The repository warns against interpreting the percentage as a blanket "Nub compatibility" figure because different Node versions, exclusion rules, and engine‑specific tests change the denominator.

Why Nub’s High Score Doesn’t Imply a Superior Runtime

Since Nub directly invokes the official Node binary, it inherits Node’s fs, http, CommonJS, N‑API, and error handling. Bun and Deno must re‑implement these capabilities, making their compatibility challenges fundamentally different.

Thus, the 98.5% score demonstrates that Nub’s enhancements rarely break existing Node behavior, but it does not prove that Nub implements a more complete Node.js runtime than Bun.

Rapid Development Over Two Months

Nub was introduced on June 15, with the GitHub repository created early June. By August 29 it reached v0.8.1 and accumulated roughly 4 100 stars. The release history shows frequent minor revisions. nub <file> – runs TypeScript, TSX, JSX, and can load YAML/TOML, respecting tsconfig.json and environment files. nub run – manages script lifecycles, workspaces, and pnpm --filter -style filtering. nubx – replaces npx and pnpm dlx, preferring local node_modules/.bin. nub install – a full‑featured package manager handling npm, pnpm, and Bun lockfiles. nub node – automatically selects or downloads Node based on .node-version, .nvmrc, or engines.node.

Cold‑start and installation benchmarks claim nubx is 19× faster than npx and nub run is 24× faster than pnpm run. The FAQ clarifies these gains apply only to CLI scheduling and cold‑start; the underlying V8 engine remains unchanged, so runtime code does not magically run faster.

Version v0.8.1 also fixed pnpm 12 lockfile handling, global install commands, and several Node version/loader compatibility issues, as listed in the official release notes.

Installation Quirks

Using the recommended install script fetched releases/latest, which at the time delivered v0.7.5, while npm’s latest tag pointed to v0.8.1. The author switched to an explicit npm install to obtain the newer version, highlighting occasional synchronization lags between distribution channels.

Getting Started in Minutes

Typical commands are intuitive from their names. After installing the latest package via npm install -g @nubjs/nub@latest, creating an index.ts with an unsupported enum and running nub index.ts on Node v22.23.1 yields:

{ status: 'ready', node: 'v22.23.1', runtime: 'node' }

This demonstrates that Nub transforms TypeScript but ultimately executes Node.js.

For existing projects, the author suggests starting with three low‑risk commands:

nub run dev
nub watch src/server.ts
nubx prisma generate

These replace common script runners, watch utilities, and npx calls. Once stable, consider nub install and nub node for package and Node version management, noting the higher risk of lockfile and CI changes.

Can Nub Replace Bun?

Nub can cover part of Bun’s development workflow, but the runtime layer remains Node.js. Bun ships its own JavaScriptCore runtime, bundler, test runner, package manager, and Bun.* APIs, and Bun 1.4 (rewritten from Zig to Rust) added 1 517 passed Node.js tests.

In contrast, Nub retains Node and V8, adding a Rust‑based tool layer without a dedicated Nub.serve() API or a binding‑required runtime. Projects that must stay within the Node ecosystem but desire a more integrated experience may find Nub a better fit.

The author recommends treating Nub as a "modern tool layer for Node.js"—use nub <file>, nub run, and nubx for low‑friction adoption, and defer package manager or Node version management changes until the tool proves stable in the project.