Awesome WebAssembly Tools

A collection of useful, language-agnostic WebAssembly development tools.

👉 Contributions are welcome! Please read the contribution guidelines. 😎

Inspecting

• WebAssembly Code Explorer | online tool
  A simple binary explorer with neat binary code highlighting.

• wasm-opt | part of Binaryen

  • Color output of s-expression format:
    wasm-opt --print test.wasm
  • Plot the callgraph using Graphviz:
    wasm-opt --print-call-graph test.wasm | dot -Tpng -o callgraph.png
  • Dump DWARF debug info sections:
    wasm-opt --dwarfdump test.wasm
  • Print function metrics:
    wasm-opt --func-metrics test.wasm

• wasm-decompile | part of WABT, article
  wasm-decompile decompiles a wasm binary into readable code. It generates output that tries to look like a "very average programming language" while still staying close to the wasm it represents.

• wasmdec | repo, online tool
  Converts WebAssembly binaries to C. Similar to wasm2c.

• wasp | repo
  Generate callgraphs, CFG and DFG graphs for wasm functions.

• wasm-objdump | part of WABT
  Print low-level details about a .wasm binary and each of its sections.

• wasm-nm | repo
  List the imported, exported, and private function symbols defined within a .wasm binary.

Static analysis

• Twiggy | repo
  Code size profiler, analyzes a binary's call graph.

• Manticore | repo, article
  Symbolic execution of WebAssembly binaries.

• Octopus | repo
  Security analysis framework for WebAssembly modules and Smart Contracts.

• Wassail | repo
  A toolkit to perform both lightweight and heavyweight static analysis of WebAssembly modules.

• wasm-opcodecnt | part of WABT
  Count wasm opcode usage statistics.

Manipulating (optimization, transformation, instrumentation)

• wasm-opt | part of Binaryen

  • Transform binary for asynchronous execution (read more in this article):
    wasm-opt test.wasm --asyncify -O3 -o asyncified.wasm
  • Instrument binary for dynamic execution tracing:
    wasm-opt test.wasm --instrument-memory --instrument-locals --log-execution -o instrumetred.wasm

• wizer | repo
  Don't wait for your Wasm module to initialize itself, pre-initialize it! Wizer instantiates your WebAssembly module, executes its initialization function, and then snapshots the initialized state out into a new WebAssembly module.

• wasm2c | part of WABT, article 1, article 2
  Takes a WebAssembly module and produces an equivalent (and runnable) C source and header.

• wasm-snip | repo
  Replaces a WebAssembly function's body with an unreachable.

• wasmonkey | repo
  Magically turns exported WASM functions into imported functions.

• wasm-meter | npm, repo
  Injects metering into webassembly binaries. This counts computation time for a given program in units of gas (and allows limiting it).

• CROW | repo
  The Wasm superdiversifier. It takes C source code or LLVM bitcode as input and generates several functionally equivalent, but diverse Wasm binaries.

Dynamic analysis (tracing, profiling)

• wasm3-strace | wapm, repo
  Structured, seamless tracing of arbitrary WebAssembly/WASI execution.

• Wasabi | home, repo
  "WebAssembly analysis using binary instrumentation", a dynamic analysis framework.

• wasmsign | repo
  A tool to add and verify digital signatures to/from WASM binaries.

• swam | repo
  A WASM interpreter with advanced tracing capabilities.

Source-level debugging

• Chrome DevTools | article

• LLDB | article

• wasminspect | repo
  An interactive and self-contained debugger for WebAssembly/WASI.

Tool development

• Tool Conventions | docs
  Documents describing conventions useful for coordinating interoperability between wasm-related tools.

• wasm2json, json2wasm | npm, repo
  A small toolkit for converting wasm binaries into json and back. Incredibly helpful for experimenting and creating your own transformations.

• walrus | repo
  Rust library for performing WebAssembly transformations in a robust and ergonomic fashion.

• wasp | repo
  C++ library designed to make it easy to work with WebAssembly modules.

• Binaryen.js | repo
  A port of Binaryen to the Web, allowing you to generate WebAssembly using JavaScript.

• wasm-tools | repo
  Rust tooling for low-level manipulation of WebAssembly modules.
  wasm-smith test case generator is of particular interest.
  wasm-shrink shrinks a Wasm file while preserving an interesting property (such as triggering a bug).

• wasm-debug | repo, crate
  A runtime-independent Rust library that provides functionality to read, transform, and write DWARF section.

• witx-codegen | repo
  A code generator to access WebAssembly standard APIs from different programming languages. Can also generate documentation.

• Articles

  • Fuzzers & Reducers as Productivity Tools

Other

• WebAssembly Opcode Table | docs

• Webassembly.sh | online tool