wasmtime
A WebAssembly runtime powered by Wasmtime
Decision gist · record as of 2026-08-14
Yes. Wasmtime is a mature, actively maintained runtime with low install friction, no runtime dependencies, and broad platform support. The monthly major-version release cycle requires discipline in dependency management, but the package is well-documented and widely used. Install it if you need to execute WebAssembly from Python; verify the license terms for your use case first.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.9 or later; 64-bit builds only on Windows, macOS, or Linux with x86_64 or arm64 architecture.
- Low friction: pure wheel distribution with no runtime dependencies.
- Actively maintained with releases every month; last commit 2026-07-20.
License · maintenance · safety
Apache-2.0 WITH LLVM-exception (unclear) — Licensed under Apache-2.0 WITH LLVM-exception. License treatment is marked unclear in the metadata, so verify the dual-license terms apply as expected for your use case before relying on it in proprietary or restricted contexts.
last release 2026-07-20 (25 days) · last repo commit 2026-07-20 · 537 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 1,897,257 downloads/mo, #3,449 on PyPI
Alternatives
Verify before relying
pip install wasmtime
from wasmtime import Store, Module, Instance
store = Store()
module = Module(store.engine, "(module (func (export \"test\")))")
instance = Instance(store, module, [])
test = instance.exports(store)["test"]
test(store)- Exact scope and stability guarantees of the monthly major-version release cycle for production use.
- Whether the Apache-2.0 WITH LLVM-exception dual-license composition is compatible with your project's license requirements.
- Performance characteristics and memory overhead when executing WebAssembly modules from Python.
What it is and what it does
Wasmtime is a Python binding to the Wasmtime WebAssembly runtime, a Bytecode Alliance project that lets you load, compile, and execute WebAssembly modules and components from within Python. It exposes a high-level API for creating stores, modules, instances, and calling exported functions, as well as importing Python functions into WebAssembly. The package ships as a precompiled wheel with no external runtime dependencies, making installation straightforward.
The runtime is actively maintained and follows Wasmtime's versioning scheme, releasing a new major version monthly. This means dependency specifications need regular updates to stay current. It supports modern Python versions (3.9 through 3.14) and PyPy on 64-bit Windows, macOS, and Linux systems. The package is suitable for embedding WebAssembly execution in Python applications, whether for sandboxed computation, plugin systems, or interoperability with WebAssembly-based libraries.
Use it for
- Execute untrusted or sandboxed WebAssembly code from Python without spawning a separate process.
- Integrate WebAssembly modules compiled from other languages into Python applications.
- Build plugin systems where plugins are distributed as WebAssembly components.
- Call Python functions from within WebAssembly modules via the import interface.
- Prototype or test WebAssembly modules interactively in Python before deployment.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Wasmtime is a mature, actively maintained runtime with low install friction, no runtime dependencies, and broad platform support. The monthly major-version release cycle requires discipline in dependency management, but the package is well-documented and widely used. Install it if you need to execute WebAssembly from Python; verify the license terms for your use case first.
Install
wasmtime on PyPI
Before you install
Low friction: pure wheel distribution with no runtime dependencies. Actively maintained with releases every month; last commit 2026-07-20. Supports Python 3.9+ on Windows, macOS, and Linux for x86_64 and arm64.
Requires Python 3.9 or later; 64-bit builds only on Windows, macOS, or Linux with x86_64 or arm64 architecture.
License in practice
Licensed under Apache-2.0 WITH LLVM-exception. License treatment is marked unclear in the metadata, so verify the dual-license terms apply as expected for your use case before relying on it in proprietary or restricted contexts.
Quickstart
pip install wasmtime
from wasmtime import Store, Module, Instance
store = Store()
module = Module(store.engine, "(module (func (export \"test\")))")
instance = Instance(store, module, [])
test = instance.exports(store)["test"]
test(store)Verify before relying
- Exact scope and stability guarantees of the monthly major-version release cycle for production use.
- Whether the Apache-2.0 WITH LLVM-exception dual-license composition is compatible with your project's license requirements.
- Performance characteristics and memory overhead when executing WebAssembly modules from Python.
Package facts
| License | Apache-2.0 WITH LLVM-exception unclear |
| Python support | Supports the current Python release >=3.9 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 25 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 1,897,257 / month, #3,449 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Programming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.9Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyProgramming Language :: RustTopic :: Software Development :: CompilersTopic :: Software Development :: Interpreters |
Evidence: wasmtime-47.0.1-py3-none-any.whl
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See also wasmer · wasmer-compiler-cranelift · qwasm · itkwasm · quickjs-rs · pyodide-py · hyperlight-sandbox-backend-wasm · mini-racer · py-mini-racer · hyperlight-sandbox-python-guest