---
id: wasmer
version: "1.1.0"
license: unclear
license_treatment: permissive
maintenance: dormant
---

# wasmer — Python extension to run WebAssembly binaries

License: permissive · Maintenance: dormant · Downloads: 556.7K/mo

## What it is and what it does

Wasmer is a WebAssembly runtime for Python that compiles and executes WASM binaries in a sandboxed environment. It wraps the Wasmer engine (written in Rust) and exposes a Python API that mirrors the standard WebAssembly API, allowing you to load WASM modules, instantiate them, and call their exported functions from Python code.

The package itself is headless—it cannot compile WASM on its own and instead relies on separate compiler packages to handle compilation. Once a module is compiled, it can be executed via the JIT or Native engine. The runtime handles memory safety and sandboxing automatically, so WASM code runs isolated from the host Python process.

Use it for:

- Execute performance-critical algorithms written in compiled languages without rewriting in Python.
- Run untrusted code safely in a sandboxed WASM environment while maintaining isolation from the host system.
- Integrate blockchain or smart-contract logic into Python applications.
- Deploy compiled WASM modules across different platforms using Python as the host language.
- Prototype or test WASM modules during development using Python tooling.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Executes WebAssembly modules from Python with a complete runtime that compiles and runs WASM binaries safely and sandboxed.

Yes, if you need to run WebAssembly modules from Python and can accept a dormant project. The package is stable and has no known vulnerabilities, but the lack of releases since 2022-01-07 means no bug fixes or compatibility updates for newer Python or system libraries. Suitable for production use of existing WASM code, but not recommended for new projects requiring ongoing maintenance or support.

## Install

pip install wasmer
uv add wasmer
poetry add wasmer

## Installing wasmer

Before you install: Low friction installation via pure-wheel distribution. However, the project is dormant—last release was 2022-01-07 and last commit 2023-09-17, with no recent maintenance activity. Suitable for stable use cases but not for active development or ongoing support.

License in practice: Licensed under MIT (permissive), allowing use in commercial and proprietary projects with minimal restrictions.

Quickstart:

pip install wasmer==1.1.0

from wasmer import engine, Store, Module, Instance

store = Store(engine.JIT())
module = Module(store, open('simple.wasm', 'rb').read())
instance = Instance(module)
result = instance.exports.sum(5, 37)

Requires a separate compiler package to compile WASM modules; the base wasmer package alone cannot compile, only execute pre-compiled modules.

Verify before relying:

- Whether the dormant status (no releases since 2022-01-07) affects compatibility with modern Python or system libraries.
- Whether the fallback py3-none-any wheel gracefully handles unsupported platforms or raises errors at import time.
- Current state of available compiler packages and whether they remain actively maintained.

## Package facts

- License: not declared (permissive)
- Python support: unspecified
- Install friction: low
- Maintenance: dormant
- Downloads: 556.7K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

webassembly runtime python, run wasm modules python, execute webassembly code, wasm interpreter python, webassembly sandbox execution, compile and run wasm, python webassembly bindings, webassembly, sandboxing

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