Wasmer

Wasmer runs your apps in fast, secure, and lightweight sandboxes: locally, in the cloud, or in your browser.

• Secure by default. You control file, network, and environment access.
• Lightweight. Fast startup with a small memory footprint.
• Ready to run. Python, JavaScript, Bash, and more from the registry.
• Embeddable. Add sandboxes to your app with the Wasmer SDK.

Run your first sandbox

Install the CLI on macOS or Linux:

curl https://get.wasmer.io -sSfL | sh

Windows (PowerShell)

iwr https://win.wasmer.io -useb | iex

Homebrew (macOS / Linux)

brew install wasmer

See the installation guide for more options.

Run Python in a sandbox:

wasmer run python/python -- -c "print('Hello from Wasmer')"

Hello from Wasmer

Or try a shell command and Cowsay:

wasmer run wasmer/bash -- -c "echo 'Hello from Wasmer'"
wasmer run syrusakbary/cowsay -- "Hello from Wasmer"

Wasmer downloads the package and caches it for future runs. Use -- to separate Wasmer options from the arguments passed to your program. To work with local files, grant access to a directory with --volume; enable host networking with --net when your program needs it. See the CLI guide for details.

No installation needed: open wasmer.sh to try a sandbox in your browser.

Wasmer SDK

Create a sandbox, choose your tools, and run code directly in your app with the Wasmer SDK.

Install the SDK

JavaScript / TypeScript (Node.js 20 or newer):

npm install @wasmer/sdk

The Rust SDK currently uses a source dependency. Clone wasmerio/wasmer-sdk, then point your application at its rust directory:

[dependencies]
wasmer-sdk = { path = "../wasmer-sdk/rust" }
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

Follow the Rust setup guide for the required toolchain and workspace patches. Crates.io publishing is currently disabled.

python -m pip install wasmer-sdk

The SDK's Python wheels support macOS and Linux on Intel and ARM64. See the Python guide.

Use Swift 6 or newer. The SDK supports macOS 12+ and iOS 27+; iOS apps require Xcode 27 or newer.

Add the package to your Package.swift dependencies:

.package(
    url: "https://github.com/wasmerio/wasmer-sdk.git",
    revision: "wasmer-sdk-swift-v0.4.0"
)

Then add the product to your target's dependencies:

.product(name: "WasmerSDK", package: "wasmer-sdk")

In Xcode, you can instead add the repository URL, select wasmer-sdk-swift-v0.4.0 as a revision, and choose the WasmerSDK product. SwiftPM downloads the prebuilt macOS binaries and iOS runtime resources.

For iOS, set the deployment target to iOS 27.0 and allow local networking in your app's Info.plist:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsLocalNetworking</key>
    <true/>
</dict>

Both platforms use import WasmerSDK and the same API. On iOS, the SDK manages a hidden WKWebView; your app does not need to display one. See the Swift guide and iOS setup guide for more details.

Run code in a sandbox

JavaScript / TypeScript

Save this as sandbox.mjs:

import { Wasmer } from "@wasmer/sdk/node";

const wasmer = new Wasmer();
const sandbox = await wasmer.sandboxes.create({
  packages: ["python/python@=3.13.20"],
});

const output = await sandbox
  .command("python", ["-c", "print('Hello from Wasmer')"])
  .run();

console.log(output.text());

Run it with node sandbox.mjs. Python executes inside the sandbox; you don't need Python installed on the host. See the JavaScript guide.

Save this as sandbox.py:

import asyncio

from wasmer_sdk import Wasmer


async def main():
    wasmer = Wasmer()
    sandbox = await wasmer.sandboxes.create(
        packages=["python/python@=3.13.20"],
    )
    output = await sandbox.command(
        "python", ["-c", "print('Hello from Wasmer')"]
    ).run()
    print(output.text())


asyncio.run(main())

Run it with python sandbox.py. See the Python guide.

Use this code in an async throws context:

import WasmerSDK

let wasmer = try Wasmer()
let sandbox = try await wasmer.sandboxes.create(
    packages: ["python/python@=3.13.20"]
)
let output = try await sandbox.command(
    "python", ["-c", "print('Hello from Swift!')"]
).run(timeout: 30)
print(try output.text())

See the Swift guide for embedding in an iOS or macOS app and more examples.

Use the same JavaScript sandbox API with the @wasmer/sdk/browser import. Execution happens in the browser. Your page needs cross-origin isolation (Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp) for worker-backed execution. Follow the browser setup guide or explore wasmer.sh.

use wasmer_sdk::{Result, Wasmer};

#[tokio::main]
async fn main() -> Result<()> {
    let wasmer = Wasmer::new()?;
    let sandbox = wasmer
        .sandboxes()
        .create()
        .package("python/python@=3.13.20")
        .await?;

    let output = sandbox
        .command("python")
        .args(["-c", "print('Hello from Wasmer')"])
        .run()
        .await?;

    println!("{}", output.text()?);
    Ok(())
}

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