TinyWasm

A tiny WebAssembly Runtime written in safe Rust

Why TinyWasm?

• Tiny: TinyWasm is designed to be as small as possible without significantly compromising performance or functionality (< 4000 LLOC).
• Portable: TinyWasm runs on any platform that Rust can target, including no_std, with minimal external dependencies.
• Safe: No unsafe code is used in the runtime (rkyv which uses unsafe code can be used for serialization, but is optional).

Status

TinyWasm passes all WebAssembly MVP tests from the WebAssembly core testsuite and is able to run most WebAssembly programs. Additionally, the current 2.0 Draft is mostly supported, with the exception of Fixed-Width SIMD and Memory64/Multiple Memories. See the Supported Proposals section for more information.

Supported Proposals

Legend
🌑 -- not available
🚧 -- in development / partialy supported
🟢 -- fully supported

Usage

See the examples directory and documentation for more information on how to use TinyWasm. For testing purposes, you can also use the tinywasm-cli tool:

$ cargo install tinywasm-cli
$ tinywasm-cli --help

Feature Flags

• std
  Enables the use of std and std::io for parsing from files and streams. This is enabled by default.
• logging
  Enables logging using the log crate. This is enabled by default.
• parser
  Enables the tinywasm-parser crate. This is enabled by default.
• archive
  Enables pre-parsing of archives. This is enabled by default.

With all these features disabled, TinyWasm only depends on core, alloc ,and libm and can be used in no_std environments. Since libm is not as performant as the compiler's math intrinsics, it is recommended to use the std feature if possible (at least for now), especially on wasm32 targets.

Inspiration

Big thanks to the authors of the following projects, which have inspired and influenced TinyWasm:

• wasmi - an efficient and lightweight WebAssembly interpreter that also runs on no_std environments
• wasm3 - a high performance WebAssembly interpreter written in C
• wazero - a zero-dependency WebAssembly interpreter written in go
• wain - a zero-dependency WebAssembly interpreter written in Rust

I encourage you to check these projects out if you're looking for more mature and feature-complete WebAssembly Runtimes.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

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

Note: The GitHub repository contains a Submodule (crates/tinywasm-parser/data) which is licensed only under the Apache License, Version 2.0. This data is generated from the WebAssembly Specification and is only used for testing purposes and not included in the final binary.