7 releases

0.2.4 Aug 22, 2022
0.2.3 Aug 19, 2022
0.2.2 Feb 10, 2021
0.1.1 Feb 2, 2021
0.1.0 Jan 31, 2021

#490 in WebAssembly

MIT license

1.5K SLoC


crates.io version crates.io downloads

A tool for formatting .wat code.

Available as a command-line tool and a library.

For more information on how to use the library, see the API docs.


To get wasmfmt, you have two options:

  1. Download a prebuilt binary from the releases page. Binaries are distributed for the following platforms:
    • Linux (x86_64 and ARM64, GNU and musl)
    • MacOS (x86_64 and ARM64)
    • Windows (x86_64 and ARM64)
  2. Build the tool manually, either from crates.io or directly from this repository.

To install from crates.io:

cargo install wasmfmt

To install from source:

cargo install --path /path/to/wasmfmt


To format a file in-place, use wasmfmt fix:

wasmfmt fix /path/to/file.wat

To determine if a file is formatted properly, use wasmfmt check:

wasmfmt check /path/to/file.wat

To simply see the formatted version of a file, use wasmfmt print:

wasmfmt print /path/to/file.wat

For more information on how to use the tool, use wasmfmt help:

wasmfmt help


To build the binary, use Cargo:

cargo build --release

The generated binary is located in target/release/wasmfmt.


To run the tests, use Cargo:

cargo test


wasmfmt is distributed under the terms of the MIT license. See LICENSE for details.


~77K SLoC