ast-serialize
Python bindings for mypy AST serialization
Decision gist · record as of 2026-08-14
Yes, if you are contributing to mypy or building tools that depend on mypy's AST serialization format. No, if you need a general-purpose Python parser—use the stdlib ast module or Ruff directly. The package is actively maintained but remains in alpha; expect breaking changes and incomplete feature coverage.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.7+; free-threaded builds need Python 3.13t or 3.14t; primarily designed for mypy integration, not standalone use.
- Medium install friction due to compiled wheels for multiple Python versions and architectures.
- Active maintenance with a release 7 days ago.
License · maintenance · safety
MIT (permissive) — MIT license permits commercial and private use with minimal restrictions; suitable for most projects.
last release 2026-08-07 (7 days) · last repo commit 2026-08-12 · 9 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 82,214,499 downloads/mo, #407 on PyPI
Alternatives
Verify before relying
pip install ast-serialize
import ast_serialize
# Requires mypy repository checkout for full integration testing
# See mypy's new-parser branch for usage examples- Whether the package is stable enough for production use outside mypy's own test suite, given its 'work in progress' status.
- Performance benchmarks comparing this parser to the stdlib ast module on typical codebases.
- Compatibility guarantees for the serialized binary format across versions.
What it is and what it does
ast_serialize is a Rust-based Python parser and AST serializer designed as a replacement for mypy's internal parser. It wraps the Ruff parser and outputs AST data in mypy's native binary format rather than Python's standard ast module objects. The package is actively maintained but explicitly marked as work in progress, intended primarily for integration into mypy's type-checking pipeline.
The package has no runtime dependencies and ships as compiled wheels for Python 3.9 through 3.15, including free-threaded variants for Python 3.13t and 3.14t. It is tightly coupled to mypy's development and testing infrastructure; standalone use outside that context is not the primary design goal.
Use it for
- Accelerating mypy's parsing phase by replacing the stdlib ast module with a faster Rust implementation.
- Testing mypy's new parser integration via the NativeParser test suite in mypy's repository.
- Developing type checkers or analysis tools that need to work with mypy's serialized AST format.
- Contributing parser improvements to mypy by iterating on the Rust codebase before upstreaming.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you are contributing to mypy or building tools that depend on mypy's AST serialization format.
No, if you need a general-purpose Python parser—use the stdlib ast module or Ruff directly. The package is actively maintained but remains in alpha; expect breaking changes and incomplete feature coverage.
Install
ast-serialize on PyPI
Before you install
Medium install friction due to compiled wheels for multiple Python versions and architectures. Active maintenance with a release 7 days ago. No runtime dependencies simplifies deployment.
Requires Python 3.7+; free-threaded builds need Python 3.13t or 3.14t; primarily designed for mypy integration, not standalone use.
License in practice
MIT license permits commercial and private use with minimal restrictions; suitable for most projects.
Quickstart
pip install ast-serialize
import ast_serialize
# Requires mypy repository checkout for full integration testing
# See mypy's new-parser branch for usage examplesVerify before relying
- Whether the package is stable enough for production use outside mypy's own test suite, given its 'work in progress' status.
- Performance benchmarks comparing this parser to the stdlib ast module on typical codebases.
- Compatibility guarantees for the serialized binary format across versions.
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.7 |
| Install friction | Medium. Platform-specific wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 7 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 82,214,499 / month, #407 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 3 - AlphaEnvironment :: ConsoleIntended Audience :: DevelopersProgramming Language :: Python :: 3Programming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.15Programming Language :: Python :: 3.9Programming Language :: RustTopic :: Software DevelopmentTyping :: Typed |
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