pycrefine

pycrefine turns compiled Python bytecode (.pyc files) back into readable Python source. It reads .pyc files written by CPython 3.9 and later, has no third-party dependencies, and works both as a command and as a library.

$ pycrefine __pycache__/report.cpython-312.pyc
def summarize(rows, limit=10):
    totals = {}
    for name, amount in rows:
        totals[name] = (totals.get(name, 0) + amount)
    return sorted(totals.items(), key=(lambda kv: -kv[1]))[:limit]

Supported Python versions

Bytecode from 3.10 onwards can only be decompiled by the Python version that wrote it (#94). pycrefine tells you which version to use, and Getting started shows how to run it under another Python in one command. Some constructs (match, async/await, yield from) are not reconstructed yet; see Limitations.

Install

python -m pip install pycrefine

Until the first release reaches PyPI, install from GitHub instead:

python -m pip install "git+https://github.com/sahebbiswas/pycrefine"

Or run it from a checkout without installing: python pycrefine.py file.pyc. Install problems (command not found, externally-managed-environment, …) are covered in Troubleshooting.

Quick start

pycrefine module.cpython-312.pyc                 # print the source
pycrefine module.cpython-312.pyc -o module.py    # save it to a file
python -m pycrefine module.cpython-312.pyc       # same, if the command is not on PATH

From Python:

import pycrefine

source = pycrefine.get_decompiler("module.cpython-312.pyc").decompile()
print(source)

Documentation

Contributing

Bug reports with the .pyc file (or the source it came from) and the Python version that compiled it are the most useful contribution. See CONTRIBUTING.md for the development setup, the checks every pull request runs, and the versioning policy.

License

MIT