Typer

Typer is a Python library for building command-line interfaces (CLIs). Developed by Sebastián Ramírez (Tiangolo), it sits on top of Click and uses Python’s type hints to automatically generate CLI commands, parameters, and help messages. Typer draws inspiration from FastAPI’s design, emphasizing concise code and clear user feedback. It is released under the MIT license and is widely used in the Python ecosystem.

Key features include automatic generation of subcommands from decorated functions, automatic help and documentation, shell auto-completion, and input parsing and validation driven by type hints. Developers can declare function parameters with standard Python types, and Typer handles parsing, prompts, and default values. It supports interactive prompts, password inputs, and confirmation prompts. It integrates with Click’s ecosystem for decorators and options while exposing a simple, Pythonic API.

Usage involves creating a Typer application object, adding commands by decorating functions with the app.command() decorator or by organizing groups for nested subcommands. The resulting CLI exposes the function signature as command parameters, with type hints guiding the expected input types. Typer is suitable for small to mid-sized CLIs and aims to reduce boilerplate while providing robust validation and user-friendly help output.