fissix
Monkeypatches to override default behavior of lib2to3.
Decision gist · record as of 2026-08-14
Yes. fissix is actively maintained, permissively licensed, has low install friction, and fills a real need for programmatic code refactoring. It is Production/Stable and used by established downstream projects. Install it if you need to build refactoring tools, automate code migrations, or integrate lib2to3 into a pipeline.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.8 or later.
- Low install friction with a single lightweight dependency (appdirs).
- Actively maintained as of August 2026 with recent commits; marked Production/Stable.
License · maintenance · safety
permissive license (permissive) — Licensed under the Python Software Foundation License Version 2, a permissive open-source license. No restrictions on commercial or private use.
last release 2024-04-24 (842 days) · last repo commit 2026-08-01 · 55 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 582,850 downloads/mo, #5,898 on PyPI
Alternatives
Verify before relying
pip install fissix
from fissix.main import StdoutRefactoringTool
from fissix import refactor
rt = StdoutRefactoringTool(['fissix.fixes.fix_import'])
rt.refactor_file('example.py', write=True)- Whether fissix's enhancements over the standard lib2to3 are documented or discoverable from the package itself.
- What specific refactoring fixes are included beyond the standard lib2to3 set.
What it is and what it does
fissix is a maintained fork of Python's lib2to3 library, the standard tool for automated code transformation and refactoring. It provides a framework for writing fixers—rules that detect and rewrite Python syntax patterns—and is commonly used to modernize codebases, migrate between Python versions, or apply large-scale code changes. The library works by parsing Python source into an abstract syntax tree, applying transformations via pluggable fixers, and writing the result back to source.
The package depends only on appdirs for cross-platform configuration directory handling. It targets developers and tools that need programmatic code refactoring capabilities, and is actively used by downstream projects like bowler (safe refactoring for modern Python) and modernize (code modernization for hybrid codebases). With a single lightweight dependency and low install friction, it integrates cleanly into build pipelines and CLI tools.
Use it for
- Automate large-scale code migrations when upgrading Python versions or dependencies.
- Build custom refactoring tools that apply project-specific syntax transformations across a codebase.
- Implement safe, repeatable code modernization workflows in CI/CD pipelines.
- Develop linting or code-quality tools that need to suggest or apply syntax fixes.
- Migrate legacy Python code patterns to modern idioms across many files at once.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
fissix is actively maintained, permissively licensed, has low install friction, and fills a real need for programmatic code refactoring. It is Production/Stable and used by established downstream projects. Install it if you need to build refactoring tools, automate code migrations, or integrate lib2to3 into a pipeline.
Install
fissix on PyPI
Before you install
Low install friction with a single lightweight dependency (appdirs). Actively maintained as of August 2026 with recent commits; marked Production/Stable. Supports current Python versions (3.8+).
Requires Python 3.8 or later.
License in practice
Licensed under the Python Software Foundation License Version 2, a permissive open-source license. No restrictions on commercial or private use.
Quickstart
pip install fissix
from fissix.main import StdoutRefactoringTool
from fissix import refactor
rt = StdoutRefactoringTool(['fissix.fixes.fix_import'])
rt.refactor_file('example.py', write=True)Verify before relying
- Whether fissix's enhancements over the standard lib2to3 are documented or discoverable from the package itself.
- What specific refactoring fixes are included beyond the standard lib2to3 set.
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.8 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packageappdirs |
| Maintenance | Actively maintained 842 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 582,850 / month, #5,898 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: Python Software Foundation LicenseTopic :: Software Development :: Libraries |
Evidence: fissix-24.4.24-py3-none-any.whl
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