Show HN: Tach – fast Python import linter in Rust with monorepo support

Tach lets you define module boundaries in a Python monorepo, automatically detect all cross-module dependencies, and then validate those dependencies. If ‘billing’ shouldn’t depend on ‘core’, you can enforce that with Tach.

You can also visualize your module graph, and use it for selective testing - running tests only on the modules impacted by your changes.

The core static analysis is done in Rust, so Tach is quick enough to be part of local development.

We’re building Tach to help engineering teams maintain velocity while scaling a monorepo. We’d love for you to give it a try!