Python CLI with Typer

Overview

Use Typer for ergonomic CLI construction. Core principle: keep CLI entry points explicit and testable.

Install

uv add typer

Quick Reference

Workflow

• Define a typer.Typer() app in cli.py.
• Keep command functions small; move logic into separate modules.
• Run CLI via uv run python -m <module> or uv run python cli.py.

Example

import typer

app = typer.Typer()

@app.command()
def greet(name: str, count: int = 1) -> None:
    for _ in range(count):
        typer.echo(f"Hello, {name}!")

if __name__ == "__main__":
    app()

Usage:

uv run python cli.py --help
uv run python cli.py Alice
uv run python cli.py Alice --count 3

Multiple commands:

import typer

app = typer.Typer()


@app.command()
def create(name: str) -> None:
    """Create a new item."""
    typer.echo(f"Creating {name}...")


@app.command()
def delete(name: str, force: bool = False) -> None:
    """Delete an item."""
    if not force:
        if not typer.confirm(f"Delete {name}?"):
            raise typer.Abort()
    typer.echo(f"Deleted {name}")


if __name__ == "__main__":
    app()

Common Mistakes

• Putting heavy business logic inside CLI functions.
• Forgetting to wire if __name__ == "__main__" for script entry.

Red Flags

• CLI guidance that ignores Typer when Typer is the chosen framework.