mypy

TypeScript

microsoft/TypeScript

Popular

Typed superset of JavaScript and the frontend default; v7 ships a Go-native compiler that is ~10x faster.

Pyright

microsoft/pyright

Popular

Fast Python type checker from Microsoft that also powers Pylance in VS Code.

ty

astral-sh/ty

TrendingNew

Astral's Rust-based Python type checker and language server, far faster than mypy; in beta.

Pyrefly

meta/pyrefly

New

Meta's Rust-based Python type checker and language server, successor to Pyre.

PHPStan

phpstan/phpstan

Popular

Static analyzer for PHP that finds bugs without running code, with strictness levels 0-10.

Sorbet

sorbet/sorbet

Fast gradual type checker for Ruby built by Stripe.

Flow

meta/flow

Legacy

Meta's static type checker for JavaScript; largely displaced by TypeScript outside Meta.