---
id: cxxfilt
version: "0.3.0"
license: BSD
license_treatment: permissive
maintenance: aging
---

# cxxfilt — Python interface to c++filt / abi::__cxa_demangle

License: permissive · Maintenance: aging · Downloads: 887.0K/mo

## What it is and what it does

cxxfilt is a thin Python wrapper around the C++ standard library's abi::__cxa_demangle function, which converts mangled C++ symbol names into human-readable form. When you compile C++ code, the compiler mangles function and class names to encode type information; this package reverses that process so you can read stack traces, debug output, or binary introspection results.

The package provides a simple demangle() function for string input and demangleb() for bytes, plus a Demangler class for custom library selection. It handles both external symbols (the default) and internal symbols when requested, and raises InvalidName for invalid input. Since it depends only on system C/C++ libraries already present on Unix systems, installation is straightforward with no Python dependencies.

Use it for:

- Decode C++ symbol names in stack traces or crash dumps for debugging compiled extensions or native libraries.
- Parse output from tools like nm or objdump that list mangled C++ symbols in binaries.
- Inspect and log readable names when introspecting C++ libraries loaded via ctypes or cffi.
- Build tooling that processes C++ build artifacts and needs human-readable symbol information.
- Demangle internal C++ symbols when analyzing template instantiations or nested class definitions.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Demangle C++ symbol names by wrapping the abi::__cxa_demangle interface, converting mangled names like _ZNSt22condition_variable_anyD2Ev into readable C++ signatures.

Yes, if you work with C++ interop or native debugging on Unix systems. The package is stable, has no dependencies, and solves a specific problem well. However, maintenance is aging (last update 2021); if you need active support or compatibility guarantees beyond Python 3.9, verify first. Not usable on Windows.

## Install

pip install cxxfilt
uv add cxxfilt
poetry add cxxfilt

## Installing cxxfilt

Before you install: Low install friction with no runtime dependencies. Last release was in 2021 and the repository is not archived, but the package has not been updated in several years; maintenance is aging.

License in practice: BSD license is permissive; you can use this package in most commercial and open-source projects without significant legal constraints.

Quickstart:

pip install cxxfilt

import cxxfilt
print(cxxfilt.demangle('_ZNSt22condition_variable_anyD2Ev'))
# Output: std::condition_variable_any::~condition_variable_any()

Requires libc and libc++/libstdc++ to be available on the system; will not work on Windows. Python 3.6 or greater.

Verify before relying:

- Whether the package works reliably with Python versions beyond those listed in classifiers (3.6 through 3.9)
- Whether custom Demangler objects can reliably locate C/C++ libraries on all supported Unix systems

## Package facts

- License: BSD (permissive)
- Python support: unspecified
- Install friction: low
- Maintenance: aging
- Downloads: 887.0K/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

c++ symbol demangling, demangle mangled names, c++filt python wrapper, abi cxa demangle, decode c++ symbols, name mangling resolution, c++ name demangler, c++-interop, debugging, symbol-resolution

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