Choosing a Language

Every Wasm toolchain reaches the same finish line — a .wasm binary that runs in the browser — but each follows a different road. The right choice depends on your existing codebase, your team’s skills, and the constraints of your project.

Decision table

Question	Rust	C / Emscripten	AssemblyScript	TinyGo
Team already writes this language?	Maybe	Maybe	If you know TS	If you know Go
Existing codebase to port?	No	Yes	No	No
Binary size priority?	Excellent	Large (libc overhead)	Excellent	Good
GC / runtime overhead?	None	Libc only	None	Minimal
Rich JS interop (strings, objects)?	Yes (wasm-bindgen)	Via ccall/cwrap	Via loader	Limited
Standard library coverage?	Full std	Full libc	Limited	Partial
Async / concurrency support?	Via futures	Via Asyncify	Limited	Limited
Learning curve (Wasm-specific)?	Medium	Low (if you know C)	Very low (TS)	Low (if you know Go)

Rust — when to choose it

Choose Rust when you are writing new Wasm-first code and want:

• The smallest possible binary (no GC, no runtime heap).
• Automatic, type-safe JS bindings via wasm-bindgen.
• A crate ecosystem designed for wasm32-unknown-unknown.
• Publishable npm packages from wasm-pack.

wasm-pack build --target web
# → pkg/ ready to npm publish

C / C++ with Emscripten — when to choose it

Choose Emscripten when you are porting an existing C/C++ library and need:

• printf, malloc, file I/O, and POSIX APIs to work without changes.
• OpenGL emulation via WebGL (-sUSE_WEBGL2).
• A single-step build from a standard Makefile or CMake project.

emcc existing_lib.c -o out.js -sEXPORTED_FUNCTIONS='["_my_api"]' -O2

AssemblyScript — when to choose it

Choose AssemblyScript when your team writes TypeScript and you need:

• A very gentle learning curve (same syntax, different numeric types).
• A tiny, self-contained Wasm module with no dependencies.
• Fast iteration without setting up a Rust or C toolchain.

npx asc assembly/index.ts --outFile build/release.wasm --optimize

TinyGo — when to choose it

Choose TinyGo when your team writes Go and you want to share pure-logic packages between a Go backend and a browser frontend:

tinygo build -o wasm.wasm -target wasm ./main.go

Note: TinyGo does not support the full Go standard library. Packages that use net, os, or reflection may not compile. Check the TinyGo package support table before committing.

Quick-pick flowchart

1. Have C/C++ code that already works? → Emscripten.
2. Team writes TypeScript and wants a quick win? → AssemblyScript.
3. Team writes Go? → TinyGo.
4. Writing new code and want the best binary size + JS interop? → Rust.

🦾 Start simple, switch later

AssemblyScript is the fastest way to ship a first Wasm module. If you later need lower-level control or richer JS bindings, migrating to Rust is straightforward because both produce the same .wasm interface — your JavaScript caller does not change.

Which toolchain is the best choice when porting an existing C library that uses printf and malloc?

wasm-pack (Rust) Emscripten (emcc) asc (AssemblyScript) tinygo

Which two toolchains produce the smallest Wasm binaries because they have no garbage collector or runtime heap?

Emscripten and TinyGo Rust and AssemblyScript AssemblyScript and TinyGo Rust and Emscripten

What is the main limitation of TinyGo when compiling Go code to Wasm?

It cannot export functions to JavaScript It only supports the wasm32-wasi target It does not support the full Go standard library It requires a separate JS loader file

Which command publishes a Rust Wasm project as an npm package?

cargo publish --target wasm32 wasm-pack publish emcc --publish npx asc --publish

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