## File: README.md

## Installation

The Wasmtime CLI can be installed on Linux and macOS (locally) with a small install
script:

```console
curl https://wasmtime.dev/install.sh -sSf | bash
```
This script installs into `$WASMTIME_HOME` (defaults to `$HOME/.wasmtime`), and executable is placed in `$WASMTIME_HOME/bin`.

After running the install script above, follow the on-screen instructions.

Windows or otherwise interested users can download installers and
binaries directly from the [GitHub
Releases](https://github.com/bytecodealliance/wasmtime/releases) page.

For additional installation options, refer to the [online book CLI installation page](https://docs.wasmtime.dev/cli-install.html).

Documentation on Wasmtime's currently supported versions can be found [in the
online book
documentation](https://docs.wasmtime.dev/stability-release.html#current-versions).

## 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 it into a WebAssembly component with:

```console
rustup target add wasm32-wasip2
rustc hello.rs --target wasm32-wasip2
```

Once compiled, you can run your component:

```console
wasmtime hello.wasm
```

You should see the following output:

```text
Hello, world!
```

(Note: make sure you installed Rust using the [`rustup`][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.)

[rustup]: https://rustup.rs

## 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-tiers.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)
* **C++** - the [`wasmtime.hh` header][c-headers]
* **[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/lang-c.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
[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.

---

## File: docs/introduction.md

# Introduction

[Wasmtime][github] is a standalone runtime for WebAssembly, WASI, and the
Component Model by the [Bytecode Alliance][BA].

[WebAssembly] (abbreviated Wasm) is a binary instruction format that is designed
to be a portable compilation target for programming languages. Wasm binaries
typically have a `.wasm` file extension. In this documentation, we'll also use
the textual representation of the binary files, which have a `.wat` file
extension.

[WASI] (the WebAssembly System Interface) defines interfaces that provide a
secure and portable way to access several operating-system-like features such as
filesystems, networking, clocks, and random numbers.

[The Component Model] is a Wasm architecture that provides a binary format for
portable, cross-language composition. More specifically, it supports the use of
interfaces via which components can communicate with each other. WASI
is defined in terms of component model interfaces.

Wasmtime runs WebAssembly code [outside of the Web], and can be used both as a
command-line utility or as a library embedded in a larger application. It
strives to be

- **Fast**: Wasmtime is built on the optimizing [Cranelift] code generator.
- **Secure**: Wasmtime's development is strongly focused on correctness and
  security.
- **Configurable**: Wasmtime uses sensible defaults, but can also be configured
  to provide more fine-grained control over things like CPU and memory
  consumption.
- **Standards Compliant**: Wasmtime passes the official WebAssembly test suite
  and the Wasmtime developers are intimately engaged with the WebAssembly
  standards process.

This documentation is intended to serve a number of purposes and within you'll
find:

* [How to use Wasmtime from a number of languages](lang.md)
* [How to install and use the `wasmtime` CLI](cli.md)
* Information about [stability](stability.md) and [security](security.md) in
  Wasmtime.
* Documentation about [contributing](contributing.md) to Wasmtime.

... and more! The source for this guide [lives on
GitHub](https://github.com/bytecodealliance/wasmtime/tree/main/docs) and
contributions are welcome!

[github]: https://github.com/bytecodealliance/wasmtime
[BA]: https://bytecodealliance.org/
[Cranelift]: https://github.com/bytecodealliance/wasmtime/blob/main/cranelift/README.md
[WebAssembly]: https://webassembly.org/
[WASI]: https://wasi.dev
[outside of the Web]: https://webassembly.org/docs/non-web/
[issue]: https://github.com/bytecodealliance/wasmtime/issues/new
[The Component Model]: https://github.com/WebAssembly/component-model