Is it possible to decompile a compiled .pyc file into a .py file?

Question

Is it possible to get some information out of the .pyc file that is generated from a .py file?

Expellant

Answer 1

Intro

Python decompilation is a hard problem, particularly for recent 3.x versions. That's why there are various tools, all with limitations and bugs.

However, Python 2.7 and earlier 3.x versions should work pretty well, and even partial decompilation is better than losing everything.

Tools to try

Uncompyle6 works, with some bugs, for Python up to 3.8, and works well for 2.7.

• Recommended option to start with as it's aiming to unify earlier forks and focusing on automated unit testing.
• The uncompyle6 GitHub page has more details.
• Works best for earlier 3.x versions, not best choice for 3.7+

If that doesn't work, it's probably best to try this next - particularly for Python 3.7+:

• decompyle3 is a fork of Uncompyle6, from same author, that should work better for 3.7 and 3.8.
• Note: this decompyle3 package is from the rocky/decompile3 repo - different spelling but same thing

If you still have problems, check the uncompyle6 and decompyle3 READMEs which link to other tools that may work better for your code.

Limitations

You can get your code back including variable names and doc strings, but without the comments.

Some code may not successfully decompile, particularly with unusual control flow, or more recent Python 3.x versions. This is due to bugs in these decompilers where Python has changed its bytecode over time.

Supporting recent Python versions

Neither uncompyle6 or decompyle3 support Python 3.9 or higher, and support for 3.7 or higher is limited.

New optimizations in Python are making decompilation harder, and both code contributions and sponsorship are lacking for both projects.

What you can do to help:

• Raise GitHub issues for these projects with bugs, after checking for similar issues - both run unit test suites on a range of Python versions.
• Sponsor these projects, particularly if they helped you

Preventing loss of code in future

Frequent Git commits or backups are clearly a good idea.

Some editors/IDEs have features to help recover deleted files even if not committed to Git. See this answer for some pointers that may work in your editor or IDE, including VS Code and JetBrains IDEs such as PyCharm, GoLand and IntelliJ.

Belostok

Thanks a lot. I had accidentally deleted my .py file instead of .pyc. This saved me from having to rewrite it from scratch. – Dunstable

For those of you here because you accidentally deleted the wrong file, I highly recommend source control! – Disaffection

^ And if you're using PyCharm, you can right-click your file/folder in the Project pane and goto Local History > Show History to revert changes. Life saver. – Chilblain

uncompyle6 is also available online at decompiler.com – Bombe

I've added a link to a new answer explaining how to undelete files in some editors and IDEs. – Belostok

uncompyle6 does not support python 3.9 at the time of this comment. – Belgae

@Belgae - good point, I've done an update mentioning limitations in more recent Python 3.x versions. – Belostok

Answer 2

You may try Easy Python Decompiler. It's based on Decompyle++ and Uncompyle2. It's supports decompiling python versions 1.0-3.3

Note: I am the author of the above tool.

Codicodices

It does its job. Good work. BTW, did you write this tool in python? – Pate

Worked well for me (easy drag and drop). It's true that a linux distro would be nice, but its not all that hard opening a windows box. – Opening

Last release in 2015 and looks like it's closed source? – Fabron

That link looks really safe. Let me click it. – Cargian

“SourceForge are (sic) abusing the trust that we and our users had put into their service in the past,” according to the GIMP project. Since 2013, SourceForge has been bundling junkware along with their installers — sometimes without a developer's permission. Don't download software from SourceForge if you can help it. – Cargian

@MacGyver Sorry but these days you can't a trust link sourceforge or not, even it's a well known domain. The answer is from 2014 when https wasn't mandatory. Yes sourceforge track record has indeed gone south and I had stopped using sourceforge a long time ago. – Codicodices

No worries. Not discrediting you. I just didn't want others to get trojens, malware, spyware, viruses, or any other internet misdemeanors. :) – Cargian

Invalid pyc/pyo file - Magic value mismatch!? – Kristenkristi

@тнαтҩυιεткιᴅϟ The tool doesn't support modern Python versions. Try using an alternative. – Codicodices

Answer 3

Yes.

I use uncompyle6 decompile (even support latest Python 3.8.0):

uncompyle6 utils.cpython-38.pyc > utils.py

and the origin python and decompiled python comparing look like this:

so you can see, ALMOST same, decompile effect is VERY GOOD.

Awn

same experience here. uncompyle6 is incredible. – Ipswich

At the time of writing does not support > 3.9 Python :( – Slowly

Answer 4

Yes, you can get it with unpyclib that can be found on pypi.

$ pip install unpyclib

Than you can decompile your .pyc file

$ python -m unpyclib.application -Dq path/to/file.pyc

Havard

I tried this and it crashed with an exception, on quite a small file with no complex code (Django settings.py) - uncompyle2 worked fine instead. -1 for that reason. – Belostok

It crashed in Python 3.6 in lib\site-packages\unpyclib\applcation.py with print __copyright -- why is it using the Python 2.7 version of print without parenthesis? – Brachycephalic

@DavidChing unpyclib's first and last release was in 2009, safe to say it's a Python 2 only program. – Fabron

Answer 5

Decompyle++ (pycdc) was the only one that worked for me: https://github.com/zrax/pycdc

was suggested in Decompile Python 2.7 .pyc

Baranowski

And this worked for me for code that was compiled with Python 2.6! – Frizette

Answer 6

I've been at this for a couple hours and finally have a solution using Decompyle++:

• visit https://cmake.org/download/ and install CMake.
• visit https://github.com/zrax/pycdc and grab a copy of this repo: pycdc-master.
• add C:\Program Files\CMake\bin to your system environment variables under PATH.

I suggest putting your pycdc-master folder into another folder, like anotherFolder.

Now you can run these commands in the command line:

• cd anotherFolder to go into the folder that has pycdc-master in it.
• cmake pycdc-master
• cd ../ to go up one directory,
• then: cmake --build anotherFolder

pycdc.exe will then be in anotherFolder\Debug.

Do something like pycdc.exe onlyhopeofgettingmycodeback.pyc in a console and it will print out the source code. I had Python 3.9.6 source code and nothing else was working.

Redbreast

Usually you create the build folder inside the repo and then inside the build folder you call cmake .. – Erda

Answer 7

Yes, it is possible.

There is a perfect open-source Python (.PYC) decompiler, called Decompyle++ https://github.com/zrax/pycdc/

Decompyle++ aims to translate compiled Python byte-code back into valid and human-readable Python source code. While other projects have achieved this with varied success, Decompyle++ is unique in that it seeks to support byte-code from any version of Python.

Rollin

While pycdc is good, it is not perfect. If you look at github.com/zrax/pycdc/issues there are over 50 individual types of problems it has in decompilation. This is however spread over the 16 or so releases of python, and both the language and code has changed drastically. It may be that for the things you have tried you haven't been able to find a problem. However, in my opinion, to classify something as "perfect", one would have to take say the entire Python library for each version, decompile it, and have it pass its own tests properly. No decompiler can do that yet. – Pyonephritis

Answer 8

Install using pip install pycompyle6

pycompyle6 filename.pyc

Activist

Answer 9

---

Title: Extracting Files from PyInstaller-Generated Executable

Problem:

How can I extract files from an executable created by PyInstaller?

Solution:

1. Clone the pyinstxtractor-ng repository:

   git clone https://github.com/pyinstxtractor/pyinstxtractor-ng.git
   

2. Extract the executable:

   cd pyinstxtractor-ng
   python pyinstxtractor-ng.py "<path_to_/dist/app>"
   

3. Install dependencies:

   sudo yum install cmake make clang
   

4. Clone the pycdc repository:

   git clone https://github.com/zrax/pycdc.git
   

5. Build and compile:

   cd pycdc
   cmake CMakeLists.txt
   make
   

6. Decompile the bytecode:

   ./pycdc "<path_to_/app_extracted/app.pyc>"
   

By following these steps, you can extract and decompile files from a PyInstaller-generated executable.

Liselisetta

Answer 10

Please try https://pylingual.io, which supports the latest Python versions (3.6 ~ 3.12). The service implements an open service that runs an NLP-based translation model + control flow analysis.

Truong

Answer 11

If you need to decompile a pyc but have python 3.9 installed you can force uncompyle6 to run. It's not perfect but it does work. Just edit site-packages\uncompyle6\bin\uncompile.py

def main_bin():
if not (sys.version_info[0:2] in ((2, 6), (2, 7), (3, 0),
                                  (3, 1), (3, 2), (3, 3),
                                  (3, 4), (3, 5), (3, 6),
                                  (3, 7), (3, 8), (3, 9)

Just add the version you have installed in the same format as the others and save. It will at least run.

Alcibiades

It does not decompile pyc made with python3.9 – Fairlie

At the time of writing does not support > 3.9 Python :( you can force it to run, but will not perform, sadly. – Slowly