wasm2wat

Convert a file to the text format and display it to the console

$ wasm2wat [file.wasm]

$ wasm2wat [file.wasm] [[-o|--output]] [file.wat]

wasm2wat [options...] <input.wasm> [<output.wat>]

--all-features
    Enable all experimental features

--debug-names
    Preserve and emit debug names from name section

--disable-all
    Disable all experimental features

--enable-<feature>
    Enable specific proposal feature (e.g., --enable-reference-types)

--fold-exprs
    Fold constant expressions (default)

--help
    Show usage help

--inline-imports
    Inline imported functions/tables

--lowercase
    Use lowercase for all names

--module
    Emit module (not script)

--no-check
    Skip input validation

--no-fold-exprs
    Disable expression folding

--preserve-imports
    Keep imports un-inlined

--print-ast
    Debug: print parsed AST

--use-strict
    Emit strict names ($func0 style)

--version
    Print version

--with-names
    Use names section if present

wasm2wat is a command-line tool from the WebAssembly Binary Toolkit (WABT) that translates compiled WebAssembly (.wasm) binaries into the human-readable WebAssembly Text Format (.wat). WebAssembly is a portable, high-performance binary code format for the web and beyond, executed in browsers and standalone runtimes.

This tool is essential for developers debugging Wasm modules, inspecting generated code from compilers like Emscripten or Rust's wasm-bindgen, or manually editing modules. It disassembles the binary's structured format—sections like types, functions, exports, and imports—into s-expr or textual syntax, preserving semantics.

By default, it validates input and outputs to stdout or a file. Options allow customization: stripping debug info, inlining functions, folding expressions, or enabling features like reference types. It's lightweight, fast, and integrates into build pipelines, CI/CD, or ad-hoc analysis.

Common workflow: compile C/Rust to Wasm, then wasm2wat input.wasm for review before optimization or deployment. Supports MVP up to recent proposals, making it a staple in Wasm ecosystems.

Requires WABT installation; input must be valid Wasm unless --no-check; limited to supported proposals; large modules may produce verbose output.

Linux: sudo apt install wabt (Ubuntu/Debian), sudo dnf install wabt (Fedora); build from source via ninja after git clone https://github.com/WebAssembly/wabt.

wasm2wat --debug-names input.wasm > output.wat
Disassembles with names preserved.

Part of WABT, launched ~2016 by Mozilla/Google WebAssembly teams during spec development; evolved with Wasm phases (MVP 2017, multi-value 2019+); current v1.0.35+ supports latest proposals.

wat2wasm(1), wasm-objdump(1), wasm-validate(1), wasm-decompile(1)