wasm-pack

Build tool for compiling Rust to WebAssembly and publishing to npm. Handles wasm-bindgen glue code generation, TypeScript type definitions, and packaging for browser, Node.js, or bundler targets. The standard workflow for Rust → Wasm → npm: write Rust with #[wasm_bindgen] attributes, run wasm-pack build, publish the resulting npm package.

Evaluated Mar 06, 2026 (0d ago) v0.13+

Homepage ↗ Repo ↗ Developer Tools webassembly wasm rust npm build-tool browser node

⚙ Agent Friendliness

/ 100

Can an agent use this?

🔒 Security

/ 100

Is it safe for agents?

⚡ Reliability

/ 100

Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality

Documentation

Error Messages

Auth Simplicity

Rate Limits

100

🔒 Security

TLS Enforcement

Auth Strength

Scope Granularity

Dep. Hygiene

Secret Handling

Rust memory safety. Wasm sandbox provides browser-side isolation. npm publishing uses standard npm security model. Open source and auditable.

⚡ Reliability

Uptime/SLA

Version Stability

Breaking Changes

Error Recovery

Best When

You're writing Rust code that needs to run in browsers or Node.js with JavaScript interop via wasm-bindgen and npm distribution.

Avoid When

You don't have Rust code to compile — or you need server-side Wasm execution rather than browser/npm distribution.

Use Cases

• Compile Rust libraries to WebAssembly npm packages that work in browser, Node.js, or bundled applications
• Build high-performance compute-heavy functions in Rust (cryptography, image processing, parsing) that run at near-native speed in browsers
• Create Rust-backed npm packages with TypeScript types auto-generated from wasm-bindgen annotations
• Integrate existing Rust codebases into JavaScript/TypeScript projects via Wasm without rewriting in JS
• Publish Wasm-powered npm packages to registries for distribution to web application developers

Not For

• Non-Rust Wasm compilation — wasm-pack is Rust-specific; use Emscripten for C/C++ or TinyGo for Go
• Server-side Wasm execution — wasm-pack targets browser/npm distribution; use wasmtime for server-side Wasm
• Pure JavaScript projects that don't need native performance — the Rust + Wasm toolchain adds significant complexity

Interface

REST API

GraphQL

gRPC

MCP Server

SDK

Webhooks

Authentication

Methods: none

OAuth: No Scopes: No

No auth for build step. Publishing to npm uses npm credentials (npm login). Publishing to private registries uses their auth.

Pricing

Model: open_source

Free tier: Yes

Requires CC: No

MIT/Apache-2.0 dual licensed. Part of the Rust+Wasm working group. Completely free.

Agent Metadata

Pagination

none

Idempotent

Full

Retry Guidance

Not documented

Known Gotchas

⚠ wasm-pack requires Rust toolchain with wasm32-unknown-unknown target — run 'rustup target add wasm32-unknown-unknown' before first build
⚠ Build target (--target web|bundler|nodejs|no-modules) changes generated JS glue code significantly — choose target based on consumption environment
⚠ wasm-bindgen version must match wasm-pack's bundled version — mismatch causes cryptic errors; pin versions in Cargo.toml
⚠ Large Rust dependency trees can take minutes to compile on first run — CI caching of cargo registry and build artifacts is essential
⚠ Generated TypeScript types may need manual refinement for complex Rust types — review .d.ts output before publishing
⚠ wasm-pack publish uses npm credentials from .npmrc or npm login — separate authentication from build step in CI

Alternatives

wasmtime-api emscripten

Full Evaluation Report

Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for wasm-pack.

$99

API endpoint ↗ Agent guide ↗ Report inaccuracy

Scores are editorial opinions as of 2026-03-06.