Tool

wasmdec

Command-line decompiler that parses a WebAssembly binary or text-format module with Binaryen and emits pseudo-C: globals, imported and defined functions with their locals and control flow, and a preamble of C helpers for WebAssembly operations. Several modules can be decompiled into one file with module-name prefixes, a memdump mode writes the module’s memory and table to files instead, and an Emscripten build of wasmdec powers an online demo. Development stopped at version 1.2.1 in 2018.

Targets: Binary · Website
Category: WebAssembly tools
Relationship: Foundation tool
Sources reviewed: 2026-10-20

Stars: 430
Last commit: 2018-11-29
Language: C++
License (GitHub): MIT

GitHub data as of 2026-11-09

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Requirements & limits

Source builds need g++ with C++14, Make, CMake and the Binaryen, cxxopts and WebAssembly testsuite submodules; GCC 7 or newer is recommended. The 1.2.1 download is a Linux x86-64 archive.
Input is a .wasm binary or .wast text module. The asm.js mode needs a compile-time flag that the Makefile does not set; parsing relies on the pinned 2018 Binaryen and may reject newer WebAssembly features.
Output is pseudo-C. Tests decompile seven bundled fixtures and spec testsuite cases and check exit status.
The examples include machine-translated code from the commercial game diep.io; rights to that output remain with the original owner.
The project is MIT; Binaryen, cxxopts and the testsuite submodules retain their own licenses.

Cite

BibTeX

@misc{wasmdec,
  title = {{wasmdec}},
  howpublished = {\url{https://github.com/wwwg/wasmdec}},
  url = {https://github.com/wwwg/wasmdec},
  urldate = {2026-10-20},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/wasmdec/}}
}

Plain text

wasmdec. https://github.com/wwwg/wasmdec (accessed 2026-10-20). Awesome REA entry: https://awesomerea.org/resources/wasmdec/

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About this entry

The description was reviewed against primary sources.

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Primary sources

README.md GitHub · wwwg/wasmdec · Revision 3d9e5ca
Makefile GitHub · wwwg/wasmdec · Revision 3d9e5ca
.gitmodules GitHub · wwwg/wasmdec · Revision 3d9e5ca
src/wasmdec.cc GitHub · wwwg/wasmdec · Revision 3d9e5ca
src/decompiler/Decompiler.cc GitHub · wwwg/wasmdec · Revision 3d9e5ca
test/tests.sh GitHub · wwwg/wasmdec · Revision 3d9e5ca
test/test-spec.sh GitHub · wwwg/wasmdec · Revision 3d9e5ca
release/install.sh GitHub · wwwg/wasmdec · Revision 3d9e5ca
mkrelease.sh GitHub · wwwg/wasmdec · Revision 3d9e5ca
LICENSE GitHub · wwwg/wasmdec · Revision 3d9e5ca
https://github.com/wwwg/wasmdec/releases/tag/1.2.1
https://github.com/WebAssembly/binaryen/tree/9f49e3d9c92703c3f5cf3589a78a3318bfe2bca4