How to Optimize Rust WASM Binary Size

To optimize Rust WASM binary size, compile in release mode with wasm-opt from the wasm-pack or wasm-bindgen-cli toolchain to strip debug symbols and dead code.

cargo build --target wasm32-unknown-unknown --release
wasm-opt -O4 target/wasm32-unknown-unknown/release/your_crate.wasm -o your_crate_optimized.wasm

Alternatively, configure your Cargo.toml to strip symbols directly during the build by adding a custom profile:

[profile.release]
opt-level = "s"
lto = true
strip = true

Then build with:

cargo build --release --target wasm32-unknown-unknown

Optimizing a Rust WASM binary is like packing a suitcase for a trip: you remove everything you don't need (dead code) and compress what remains (stripping symbols) to make it as small as possible. This matters because smaller files load faster in web browsers, improving user experience. You use this process whenever you are preparing a Rust library or application to run on the web.