#xwasm #webassembly #pxwasm


Collection of command-line utilities and corresponding Rust api for producing pxwasm-compatible executables

2 releases

Uses old Rust 2015

0.6.2 May 14, 2019
0.6.1 May 14, 2019

#459 in WebAssembly




Build Status

Collection of WASM utilities used in Susy and WASM contract development

Build tools for cargo

Easiest way to use is to install via cargo install:

cargo install xwasm-utils-cli --bin xwasm-build

Symbols pruning (xwasm-prune)

cargo install xwasm-utils-cli --bin xwasm-prune
xwasm-prune <input_xwasm_binary.xwasm> <output_xwasm_binary.xwasm>

This will optimize WASM symbols tree to leave only those elements that are used by contract call function entry.

Gas counter (xwasm-gas)

For development puposes, raw WASM contract can be injected with gas counters (the same way as it done by Susy runtime when running contracts)

cargo install xwasm-utils-cli --bin xwasm-gas
xwasm-gas <input_xwasm_binary.xwasm> <output_xwasm_binary.xwasm>

Externalization (xwasm-ext)

Susy WASM runtime provides some library functions that can be commonly found in libc. WASM binary size can be reduced and performance may be improved if these functions are used. This utility scans for invocations of the following functions inside the WASM binary:

  • _malloc,
  • _free,
  • _memcpy,
  • _memset,
  • _memmove

And then substitutes them with invocations of the imported ones. Should be run before xwasm-opt for better results.

cargo install xwasm-utils-cli --bin xwasm-ext
xwasm-ext <input_xwasm_binary.xwasm> <output_xwasm_binary.xwasm>


All executables use corresponding api methods of the root crate and can be combined in other build tools.


xwasm-utils is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), at your choice.

See LICENSE-APACHE, and LICENSE-MIT for details.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in xwasm-utils by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


~10K SLoC