beartype/beartype

Health v2 · maintenance only

Adoption not part of the score

3486 stars · 81 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

Beartype is a pure-Python, PEP-compliant runtime type checker that validates type hints at near-real-time speed with O(1) constant-time checks. It can implicitly type-check all annotated callables, classes, and variable assignments across a package via a single import hook.

Use cases

• enforce type hints at runtime in Python
• validate function arguments against type annotations
• catch type errors in production without performance overhead
• type-check an entire Python package with one line
• validate data structures against complex PEP 484/585 type hints

When to choose

• you want runtime type checking with negligible overhead
• you need PEP-compliant validation of modern type hints (generics, unions, Annotated)
• you want a zero-dependency pure-Python solution
• you want to opt a whole package into type checking via an import hook

When to avoid

• you only need static type checking at edit time (use mypy or pyright)
• you need runtime schema validation with coercion or detailed error schemas (consider pydantic)
• your codebase is not Python

Facets

library · maturity active

type-system testing developer-tools developer-tools programming-languages performance python cross-platform type-checking type-hints runtime-validation pep-compliant pure-python

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