mypy
The original and canonical static type checker for Python — the PEP 484 reference implementation that defined the modern Python type-hint ecosystem.
type-checking-frameworksRecently released
87
Hero Score
Popularity
88
Performance
70
Ecosystem
100
Maturity
100
Dev Experience
75
⭐ 20,451 stars⬇ 34.1M downloads/wkFirst release: Sep 2009Last release: May 2026
Async Support: YesPlugin Extensions: Very highSpeed: MediumDoc Quality: Very highLearning Curve: Medium
Pros
- • Reference implementation of PEP 484 with the deepest, most battle-tested type semantics
- • Massive plugin ecosystem covering Django, SQLAlchemy, Pydantic, attrs, and more
- • Largest tutorial and Stack Overflow footprint of any Python type checker
Cons
- • Significantly slower than Rust-based checkers like ty and pyrefly on large codebases
- • Strictness defaults are loose — getting full coverage requires careful config tuning
- • Inference on complex generics and decorators can lag behind newer typing PEPs