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A WebAssembly interpreter written in pure Python
WebAssembly Python
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pywasm: A WebAssembly interpreter written in pure Python.

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A WebAssembly interpreter written in pure Python.

The wasm version currently in use is: WebAssembly Core Specification W3C Working Draft, 4 September 2018. Just like Firefox or Chrome does.


$ pip3 install pywasm

Some simple examples

  1. First we need a wasm module! Grab our ./examples/fib.wasm file and save a copy in a new directory on your local machine. Note: fib.wasm was compiled from ./examples/fib.c by WasmFiddle.

  2. Now, compile and instantiate WebAssembly modules directly from underlying sources. This is achieved using the pywasm.load method.

import pywasm
# pywasm.on_debug()

vm = pywasm.load('./examples/fib.wasm')
r = vm.exec('fib', [10])
print(r) # 55

A brief description for ./examples

File Description
./examples/add.wasm Export i32.add function
./examples/env.wasm Call python/native function in wasm
./examples/fib.wasm Fibonacci, which contains loop and recursion
./examples/str.wasm Export a function which returns string
./examples/sum.wasm Equal difference series summation


python ./tests/

Tested in the following environments:

  • Python 3.7.3
  • Python 3.6.5




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