# Why Tach?

## Modern Codebases are Complex

Many Python projects start as small, simple scripts. But over time, they tend to grow into a complex web of thousands of modules, with messy dependencies that can cause bugs and slow down development.

Large Python codebases become especially difficult when:

- Refactoring is risky because dependencies are opaque
- Adding features becomes a fearful experience
- Changes have unknown ripple effects
- Teams need boundaries between code areas
- Module APIs aren't explicit 

## Existing Solutions Fall Short

There are some existing tools for managing Python dependencies:

- **Type checkers**: Help catch issues with dynamic typing, but don't enforce module boundaries
- **Linters**: Can alert on styling issues, but don't generally analyze module structure
- **Package managers**: Manage external dependencies, but don't handle internal module dependencies
- **Tests**: Verify functionality, but don't enforce architecture
- **Manually managed dependency rules**: Hard to maintain and inconsistent

## Tach is Purpose-Built for Modularity

Tach is designed to solve this specific problem. It gives you tools to:

- **Define module boundaries** in your codebase
- **Control dependencies** between modules
- **Define explicit public interfaces** to prevent deep coupling
- **Gradually adopt** in existing projects
- **Integrate with your workflow**: CI, pre-commit, etc.

Tach helps you build and maintain a modular Python architecture that can scale with your project as it grows. 