wasmdis

wasmdis is an open‑source command‑line utility designed to translate WebAssembly binary modules into a human‑readable textual representation. The tool is primarily used for debugging, reverse engineering, and educational purposes, allowing developers to inspect the low‑level structure of WebAssembly (Wasm) code without requiring access to the original source.

The project originated in 2018 as a contribution to the broader WebAssembly tooling ecosystem, addressing a gap where existing disassemblers either lacked support for the latest Wasm specifications or provided output that was difficult to parse. wasmdis implements the official WebAssembly binary format specification, supporting both the core 1.0 format and extensions such as threads, SIMD, and reference types. Its output mirrors the WebAssembly Text format (WAT) but retains additional annotation options, such as opcode offsets, section boundaries, and type signatures, to aid low‑level analysis.

wasmdis is written in Rust, leveraging the language’s strong safety guarantees and performance characteristics. The codebase depends on the wasmparser crate for binary parsing and provides a small wrapper that formats the parsed instructions. The utility can be installed via cargo, the Rust package manager, or downloaded as a pre‑compiled binary for major operating systems. Command‑line options include the ability to filter specific sections, display raw byte offsets, and output coloring for improved readability.

Since its initial release, wasmdis has been integrated into several development workflows, including continuous‑integration pipelines that verify the correctness of generated Wasm modules, and academic projects that study the impact of compiler optimizations on binary size and instruction patterns. The project is maintained on a public repository, where contributions are accepted via pull requests under an MIT license, encouraging community involvement in extending support for emerging WebAssembly proposals.