Has anyone tried the new Basilisk Python type checker?

For now I would stick with an established tool unless Basilisk solves a specific problem you have. I have been using the usual combination of a fast formatter or linter and a mature type checker, while newer options such as ty are also worth watching. A full conformance score is useful, but ecosystem support, editor integration, bug reports, and stability matter just as much.

The development process makes me cautious. The commit history and project documentation suggest that automated coding tools may have been used repeatedly to make more conformance tests pass. That can produce impressive benchmark numbers, but it may also lead to special cases or hacks rather than a coherent, maintainable checker. I would test it on a real codebase before depending on it.

It seems to have been released very recently, so the small user base and low star count may simply reflect its age. The strongest public validation so far appears to be a typing-community member reviewing and accepting a conformance-suite change. Passing that suite is encouraging, but it does not automatically prove that inference, narrowing, diagnostics, or behavior outside the standardized tests are reliable.