Pyright is a fast type checker meant for large Python source bases. It can run in a “watch” mode and performs fast incremental updates when files are modified.

Pyright does not require a Python environment or imported third-party packages to be installed.

Pyright supports configuration files that provide granular control over settings. Different “execution environments” can be associated subdirectories within a source base. Each environment can specify different module search paths, python language versions, and platform targets.

Pyright supports:

• PEP 484 type hints including generics
• PEP 526 syntax for variable annotations
• PEP 544 structural subtyping
• Type inference for function return values, instance variables, class variables, and globals
• Smart type constraints that understand conditional code flow constructs like if/else statements

Pyright includes a recent copy of the stdlib type stubs from Typeshed. It can be configured to use another (perhaps more recent or modified) copy of the Typeshed type stubs. Of course, it also works with custom type stub files that are part of your project.

For more details, refer to the README on the Pyright GitHub site.