`wasmtime`

A standalone runtime for WebAssembly

A Bytecode Alliance project

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## Installation The Wasmtime CLI can be installed on Linux and macOS (locally) with a small install script: ```sh curl https://wasmtime.dev/install.sh -sSf | bash ``` Windows or otherwise interested users can download installers and binaries directly from the [GitHub Releases](https://github.com/bytecodealliance/wasmtime/releases) page. ## Example If you've got the [Rust compiler installed](https://www.rust-lang.org/tools/install) then you can take some Rust source code: ```rust fn main() { println!("Hello, world!"); } ``` and compile/run it with: ```sh $ rustup target add wasm32-wasi $ rustc hello.rs --target wasm32-wasi $ wasmtime hello.wasm Hello, world! ``` (Note: make sure you installed Rust using the `rustup` method in the official instructions above, and do not have a copy of the Rust toolchain installed on your system in some other way as well (e.g. the system package manager). Otherwise, the `rustup target add...` command may not install the target for the correct copy of Rust.) ## Features * **Fast**. Wasmtime is built on the optimizing [Cranelift] code generator to quickly generate high-quality machine code either at runtime or ahead-of-time. Wasmtime is optimized for efficient instantiation, low-overhead calls between the embedder and wasm, and scalability of concurrent instances. * **[Secure]**. Wasmtime's development is strongly focused on correctness and security. Building on top of Rust's runtime safety guarantees, each Wasmtime feature goes through careful review and consideration via an [RFC process]. Once features are designed and implemented, they undergo 24/7 fuzzing donated by [Google's OSS Fuzz]. As features stabilize they become part of a [release][release policy], and when things go wrong we have a well-defined [security policy] in place to quickly mitigate and patch any issues. We follow best practices for defense-in-depth and integrate protections and mitigations for issues like Spectre. Finally, we're working to push the state-of-the-art by collaborating with academic researchers to formally verify critical parts of Wasmtime and Cranelift. * **[Configurable]**. Wasmtime uses sensible defaults, but can also be configured to provide more fine-grained control over things like CPU and memory consumption. Whether you want to run Wasmtime in a tiny environment or on massive servers with many concurrent instances, we've got you covered. * **[WASI]**. Wasmtime supports a rich set of APIs for interacting with the host environment through the [WASI standard](https://wasi.dev). * **[Standards Compliant]**. Wasmtime passes the [official WebAssembly test suite](https://github.com/WebAssembly/testsuite), implements the [official C API of wasm](https://github.com/WebAssembly/wasm-c-api), and implements [future proposals to WebAssembly](https://github.com/WebAssembly/proposals) as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too. [Wasmtime]: https://github.com/bytecodealliance/wasmtime [Cranelift]: https://cranelift.dev/ [Google's OSS Fuzz]: https://google.github.io/oss-fuzz/ [security policy]: https://bytecodealliance.org/security [RFC process]: https://github.com/bytecodealliance/rfcs [release policy]: https://docs.wasmtime.dev/stability-release.html [Secure]: https://docs.wasmtime.dev/security.html [Configurable]: https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html [WASI]: https://docs.rs/wasmtime-wasi/latest/wasmtime_wasi/ [Standards Compliant]: https://docs.wasmtime.dev/stability-wasm-proposals-support.html ## Language Support You can use Wasmtime from a variety of different languages through embeddings of the implementation. Languages supported by the Bytecode Alliance: * **[Rust]** - the [`wasmtime` crate] * **[C]** - the [`wasm.h`, `wasi.h`, and `wasmtime.h` headers][c-headers], [CMake](crates/c-api/CMakeLists.txt) or [`wasmtime` Conan package] * **C++** - the [`wasmtime-cpp` repository][wasmtime-cpp] or use [`wasmtime-cpp` Conan package] * **[Python]** - the [`wasmtime` PyPI package] * **[.NET]** - the [`Wasmtime` NuGet package] * **[Go]** - the [`wasmtime-go` repository] * **[Ruby]** - the [`wasmtime` gem] Languages supported by the community: * **[Elixir]** - the [`wasmex` hex package] * **Perl** - the [`Wasm` Perl package's `Wasm::Wasmtime`] [Rust]: https://bytecodealliance.github.io/wasmtime/lang-rust.html [C]: https://bytecodealliance.github.io/wasmtime/examples-c-embed.html [`wasmtime` crate]: https://crates.io/crates/wasmtime [c-headers]: https://bytecodealliance.github.io/wasmtime/c-api/ [Python]: https://bytecodealliance.github.io/wasmtime/lang-python.html [`wasmtime` PyPI package]: https://pypi.org/project/wasmtime/ [.NET]: https://bytecodealliance.github.io/wasmtime/lang-dotnet.html [`Wasmtime` NuGet package]: https://www.nuget.org/packages/Wasmtime [Go]: https://bytecodealliance.github.io/wasmtime/lang-go.html [`wasmtime-go` repository]: https://pkg.go.dev/github.com/bytecodealliance/wasmtime-go [wasmtime-cpp]: https://github.com/bytecodealliance/wasmtime-cpp [`wasmtime` Conan package]: https://conan.io/center/wasmtime [`wasmtime-cpp` Conan package]: https://conan.io/center/wasmtime-cpp [Ruby]: https://bytecodealliance.github.io/wasmtime/lang-ruby.html [`wasmtime` gem]: https://rubygems.org/gems/wasmtime [Elixir]: https://docs.wasmtime.dev/lang-elixir.html [`wasmex` hex package]: https://hex.pm/packages/wasmex [`Wasm` Perl package's `Wasm::Wasmtime`]: https://metacpan.org/pod/Wasm::Wasmtime ## Documentation [📚 Read the Wasmtime guide here! 📚][guide] The [wasmtime guide][guide] is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, [it can also help you do that][contributing]! [contributing]: https://bytecodealliance.github.io/wasmtime/contributing.html [guide]: https://bytecodealliance.github.io/wasmtime --- It's Wasmtime.