Pywasm: A WebAssembly interpreter written in pure Python.

A WebAssembly interpreter written in pure Python, no third-party libraries are used.

The wasm version currently in use is: WebAssembly Specification, Release 2.0 (Draft 2025-04-25).

Also requires Python version >= 3.12.

Installation

$ pip install pywasm

Some simple examples

1. First we need a wasm module! Grab our example/fibonacci/bin/fibonacci.wasm file and save a copy in a new directory on your local machine.

2. Now, instantiate WebAssembly modules directly from underlying sources. This is achieved using the Runtime.instance_from_file method.

import pywasm
pywasm.log.lvl = 1

runtime = pywasm.core.Runtime()
m = runtime.instance_from_file('example/fibonacci/bin/fibonacci.wasm')
r = runtime.invocate(m, 'fibonacci', [10])
print(f'fibonacci(10) = {r[0]}')

A brief description for example

File	Description
example/blake2b.py	Blake2b hashing algorithm
example/blake2b_direct.py	Make the hash result returned as a value, not as an output parameter
example/fibonacci.py	Fibonacci, which contains loop and recursion
example/fibonacci_env.py	Call python/native function in wasm
example/pi.py	Calculate π using the agm algorithm
example/wasi_print.py	Execute a wasi program and print poem "The Zen of Python"

Test

$ python test/example.py
$ python test/spec.py
$ python test/wasi.py

Thanks

• wagon
• warpy
• zstdpy

License

MIT