Typer

Typer generates CLIs from Python type hints. Built on Click, it reduces boilerplate while keeping Click's ecosystem.

Recipe

import typer
 
app = typer.Typer()
 
@app.command()
def greet(name: str, loud: bool = False):
    msg = f"Hello, {name}"
    typer.echo(msg.upper() if loud else msg)
 
if __name__ == "__main__":
    app()

When to reach for this:

• Project already uses type hints throughout
• Fast CLI prototyping from function signatures
• Click power with less decorator boilerplate

Working Example

import typer
from pathlib import Path
from typing import Optional
from enum import Enum
 
app = typer.Typer(help="Invoice management CLI")
 
class OutputFormat(str, Enum):
    json = "json"
    csv = "csv"
 
@app.command()
def export(
    invoice_id: int = typer.Argument(..., help="Invoice ID"),
    output: Path = typer.Option("out.json", help="Output file"),
    format: OutputFormat = OutputFormat.json,
    verbose: bool = typer.Option(False, "--verbose", "-v"),
):
    if verbose:
        typer.echo(f"Exporting invoice {invoice_id} as {format.value}", err=True)
    # export logic
    typer.echo(f"Written to {output}")
 
@app.command()
def list(limit: int = typer.Option(10, min=1, max=100)):
    typer.echo(f"Listing {limit} invoices")
 
if __name__ == "__main__":
    app()

What this demonstrates:

• Type hints drive argument types and help text
• Enum becomes Choice automatically
• Path validates file paths
• typer.Option and typer.Argument for metadata

Deep Dive

Type Mapping

Gotchas

• Missing type hints - Typer cannot infer arguments. Fix: annotate every parameter.
• Complex validation - hints are not enough. Fix: use Pydantic models or callback validators.
• Bool positional confusion - bool as positional is tricky. Fix: use typer.Option for flags.
• Not installing typer[all] - missing shell completion extras. Fix: uv add "typer[all]" for dev.
• Breaking changes between Typer versions - pin version. Fix: lock in pyproject.toml.

Alternatives

FAQs

Related

• Click - underlying framework
• argparse - stdlib option
• Config & Environment - settings
• CLI Best Practices - design rules

Stack versions: This page was written for Python 3.14.0, FastAPI 0.115+, Django 5.2, Flask 3.1, Pydantic 2, PyTorch 2.6+, pandas 2.2+, Polars 1.x, ruff 0.9+, and uv 0.6+.