pyupgrade
A tool to automatically upgrade syntax for newer versions.
Decision gist · record as of 2026-08-14
Yes. pyupgrade is actively maintained, has no known vulnerabilities, installs with minimal friction, and solves a real problem for teams modernizing Python codebases. Its permissive MIT license and broad adoption (top 5000 PyPI packages) make it a low-risk addition to development workflows, especially when integrated as a pre-commit hook to enforce syntax consistency automatically.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later to run the tool itself; the code being upgraded can target older Python versions via command-line flags.
- Low friction install with a single runtime dependency (tokenize-rt).
- Active maintenance with recent releases; last commit 2026-08-13 and 4113 repository stars indicate steady use and support.
License · maintenance · safety
MIT (permissive) — MIT license permits unrestricted use, modification, and distribution in both open-source and commercial projects with minimal restrictions.
last release 2025-11-19 (268 days) · last repo commit 2026-08-13 · 4,113 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 1,860,922 downloads/mo, #3,483 on PyPI
Alternatives
Verify before relying
pip install pyupgrade
# Run on a single file
pyupgrade myfile.py
# Or add to .pre-commit-config.yaml:
# - repo: https://github.com/asottile/pyupgrade
# rev: v3.21.2
# hooks:
# - id: pyupgrade- Whether all syntax rewrites are safe to apply automatically without manual review in large codebases
- Performance characteristics when processing very large Python files or projects
- Specific Python version targets supported by command-line flags beyond those shown in examples
What it is and what it does
pyupgrade is a command-line tool and pre-commit hook that scans Python source files and automatically rewrites code to use modern syntax patterns. It handles a wide range of modernizations: converting old-style set and dict construction to comprehensions, replacing printf-style string formatting with `.format()` calls, removing unnecessary `u''` prefixes, simplifying `super()` calls, removing Python 2 compatibility code and six library usage, and eliminating deprecated unittest method aliases. The tool is driven by command-line flags that control which Python version's features to target, allowing gradual modernization of codebases.
It runs as a standalone tool on individual files or directories, or integrates into pre-commit hooks to enforce modernization on every commit. The single runtime dependency is tokenize-rt, which handles Python tokenization. The tool requires Python 3.10 or later to run, though it can modernize code written for older Python versions by removing version-specific compatibility patterns.
Use it for
- Automatically upgrade a legacy codebase from Python 2 to Python 3 by removing six imports and compatibility shims
- Enforce consistent modern syntax in CI/CD pipelines via pre-commit hooks to catch outdated patterns before merge
- Batch-modernize string formatting from printf-style to `.format()` across thousands of lines of code
- Remove deprecated unittest method aliases (e.g., `failUnlessEqual` → `assertEqual`) from test suites
- Simplify class definitions by removing unnecessary `object` inheritance and rewriting metaclass declarations
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
pyupgrade is actively maintained, has no known vulnerabilities, installs with minimal friction, and solves a real problem for teams modernizing Python codebases. Its permissive MIT license and broad adoption (top 5000 PyPI packages) make it a low-risk addition to development workflows, especially when integrated as a pre-commit hook to enforce syntax consistency automatically.
Install
pyupgrade on PyPI
Before you install
Low friction install with a single runtime dependency (tokenize-rt). Active maintenance with recent releases; last commit 2026-08-13 and 4113 repository stars indicate steady use and support.
Requires Python 3.10 or later to run the tool itself; the code being upgraded can target older Python versions via command-line flags.
License in practice
MIT license permits unrestricted use, modification, and distribution in both open-source and commercial projects with minimal restrictions.
Quickstart
pip install pyupgrade
# Run on a single file
pyupgrade myfile.py
# Or add to .pre-commit-config.yaml:
# - repo: https://github.com/asottile/pyupgrade
# rev: v3.21.2
# hooks:
# - id: pyupgradeVerify before relying
- Whether all syntax rewrites are safe to apply automatically without manual review in large codebases
- Performance characteristics when processing very large Python files or projects
- Specific Python version targets supported by command-line flags beyond those shown in examples
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagetokenize-rt |
| Maintenance | Actively maintained 268 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 1,860,922 / month, #3,483 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Programming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPy |
Evidence: pyupgrade-3.21.2-py2.py3-none-any.whl
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See also absolufy-imports · reorder-python-imports · to-requirements.txt · google-pasta · yesqa · add-trailing-comma · darker · django-upgrade · update · unidiff2